computer_science.jsonl

{"answer": "Binary search halves a sorted array each step, reaching O(log n) time.", "choices": null, "id": "cs_0001", "kind": "concept", "lang": "en", "question": "How does binary search work?", "steps": ["Require a sorted array.", "Compare middle to target.", "Recurse into the matching half."], "subject": "computer_science", "text": "Answer: Halve sorted array each step.\nSteps:\n1. Require a sorted array.\n2. Compare middle to target.\n3. Recurse into the matching half.", "topic": "algorithms"}
{"answer": "Binary search runs in O(log n) time on sorted data.", "choices": {"A": "O(n)", "B": "O(log n)", "C": "O(n log n)", "D": "O(1)"}, "id": "cs_0002", "kind": "multiple_choice", "lang": "en", "question": "What is the time complexity of binary search?", "steps": ["Halving each step.", "Log steps total.", "Select option B."], "subject": "computer_science", "text": "Answer: O(log n).\nSteps:\n1. Halving each step.\n2. Log steps total.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "Finding 7 takes 4 comparisons: mids 8, 4, 6, then 7.", "choices": null, "id": "cs_0003", "kind": "worked_example", "lang": "en", "question": "Binary search for 7 in [1..15]. How many comparisons?", "steps": ["Mid of 1-15 is 8: go left.", "Mid of 1-7 is 4: go right.", "Mid of 5-7 is 6: go right; mid of 7-7 is 7: found in 4."], "subject": "computer_science", "text": "Answer: 4 comparisons.\nSteps:\n1. Mid of 1-15 is 8: go left.\n2. Mid of 1-7 is 4: go right.\n3. Mid of 5-7 is 6: go right; mid of 7-7 is 7: found in 4.", "topic": "algorithms"}
{"answer": "Binární vyhledávání půlí seřazené pole a běží v čase O(log n).", "choices": null, "id": "cs_0004", "kind": "concept", "lang": "cs", "question": "Co je binární vyhledávání?", "steps": ["Vyžaduje seřazené pole.", "Porovná střed s cílem.", "Pokračuje v polovině."], "subject": "computer_science", "text": "Answer: Půlení seřazeného pole.\nSteps:\n1. Vyžaduje seřazené pole.\n2. Porovná střed s cílem.\n3. Pokračuje v polovině.", "topic": "algorithms"}
{"answer": "Quicksort averages O(n log n) via partitioning around pivots.", "choices": {"A": "O(n)", "B": "O(log n)", "C": "O(n log n)", "D": "O(n^2) average"}, "id": "cs_0005", "kind": "multiple_choice", "lang": "en", "question": "What is quicksort's average complexity?", "steps": ["Partition around pivot.", "Recurse both sides.", "Select option C."], "subject": "computer_science", "text": "Answer: O(n log n).\nSteps:\n1. Partition around pivot.\n2. Recurse both sides.\n3. Select option C.\nAnswer: (C)", "topic": "algorithms"}
{"answer": "Bubble sort needs 2 swaps: [3,1,2] -> [1,3,2] -> [1,2,3].", "choices": null, "id": "cs_0006", "kind": "worked_example", "lang": "en", "question": "How many swaps bubble-sort [3,1,2]?", "steps": ["Compare 3,1: swap to [1,3,2].", "Compare 3,2: swap to [1,2,3].", "Total swaps = 2."], "subject": "computer_science", "text": "Answer: 2 swaps.\nSteps:\n1. Compare 3,1: swap to [1,3,2].\n2. Compare 3,2: swap to [1,2,3].\n3. Total swaps = 2.", "topic": "algorithms"}
{"answer": "Merge sort splits the array, sorts halves, and merges them in O(n log n).", "choices": null, "id": "cs_0007", "kind": "concept", "lang": "en", "question": "How does merge sort work?", "steps": ["Divide array in half.", "Sort each half.", "Merge sorted halves."], "subject": "computer_science", "text": "Answer: Divide, sort, merge.\nSteps:\n1. Divide array in half.\n2. Sort each half.\n3. Merge sorted halves.", "topic": "algorithms"}
{"answer": "Lineárním vyhledáváním najdeme 5 na 3. porovnání.", "choices": null, "id": "cs_0008", "kind": "worked_example", "lang": "cs", "question": "Kolik porovnání najde 5 v [2,4,5,7] lineárně?", "steps": ["Porovnej 2: ne.", "Porovnej 4: ne.", "Porovnej 5: ano, celkem 3."], "subject": "computer_science", "text": "Answer: 3 porovnání.\nSteps:\n1. Porovnej 2: ne.\n2. Porovnej 4: ne.\n3. Porovnej 5: ano, celkem 3.", "topic": "algorithms"}
{"answer": "Merge sort is stable: equal elements keep their order.", "choices": {"A": "Merge sort", "B": "Quicksort", "C": "Heap sort", "D": "Selection sort"}, "id": "cs_0009", "kind": "multiple_choice", "lang": "en", "question": "Which sort is stable?", "steps": ["Stable keeps equal order.", "Merge sort qualifies.", "Select option A."], "subject": "computer_science", "text": "Answer: Merge sort.\nSteps:\n1. Stable keeps equal order.\n2. Merge sort qualifies.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "Every recursion needs a base case that stops the calls.", "choices": null, "id": "cs_0010", "kind": "concept", "lang": "en", "question": "What is a base case in recursion?", "steps": ["Recursive calls shrink input.", "Base case returns directly.", "Without it, stack overflows."], "subject": "computer_science", "text": "Answer: Stopping condition.\nSteps:\n1. Recursive calls shrink input.\n2. Base case returns directly.\n3. Without it, stack overflows.", "topic": "algorithms"}
{"answer": "factorial(5) = 120, from 5 x 4 x 3 x 2 x 1.", "choices": null, "id": "cs_0011", "kind": "worked_example", "lang": "en", "question": "Compute factorial(5) recursively.", "steps": ["5 x factorial(4).", "Unwind: 5x4x3x2x1.", "Result = 120."], "subject": "computer_science", "text": "Answer: 120.\nSteps:\n1. 5 x factorial(4).\n2. Unwind: 5x4x3x2x1.\n3. Result = 120.", "topic": "algorithms"}
{"answer": "DFS uses a stack to explore deep before wide.", "choices": {"A": "Queue", "B": "Heap", "C": "Tree", "D": "Stack"}, "id": "cs_0012", "kind": "multiple_choice", "lang": "en", "question": "Which structure does DFS use?", "steps": ["DFS goes deep first.", "Stack gives LIFO.", "Select option D."], "subject": "computer_science", "text": "Answer: Stack.\nSteps:\n1. DFS goes deep first.\n2. Stack gives LIFO.\n3. Select option D.\nAnswer: (D)", "topic": "algorithms"}
{"answer": "Rekurze je volání funkce sebe sama s ukončovací podmínkou.", "choices": null, "id": "cs_0013", "kind": "concept", "lang": "cs", "question": "Co je rekurze?", "steps": ["Funkce volá sebe.", "Vstup se zmenšuje.", "Báze zastaví volání."], "subject": "computer_science", "text": "Answer: Sebevolání s bází.\nSteps:\n1. Funkce volá sebe.\n2. Vstup se zmenšuje.\n3. Báze zastaví volání.", "topic": "algorithms"}
{"answer": "BFS expands level by level, so first visit is shortest in unweighted graphs.", "choices": {"A": "Longest path", "B": "Shortest path", "C": "Random path", "D": "No path"}, "id": "cs_0014", "kind": "multiple_choice", "lang": "en", "question": "What does BFS find in unweighted graphs?", "steps": ["Levels expand evenly.", "First hit is nearest.", "Select option B."], "subject": "computer_science", "text": "Answer: Shortest path.\nSteps:\n1. Levels expand evenly.\n2. First hit is nearest.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "Insertion sort gives [2,4,5]: insert 2 first, then 4.", "choices": null, "id": "cs_0015", "kind": "worked_example", "lang": "en", "question": "Insertion-sort [5,2,4]. What are the steps?", "steps": ["Insert 2 before 5: [2,5,4].", "Insert 4 between: [2,4,5].", "Sorted in 2 insertions."], "subject": "computer_science", "text": "Answer: [2,4,5].\nSteps:\n1. Insert 2 before 5: [2,5,4].\n2. Insert 4 between: [2,4,5].\n3. Sorted in 2 insertions.", "topic": "algorithms"}
{"answer": "Big-O bounds growth rate, ignoring constants and small inputs.", "choices": null, "id": "cs_0016", "kind": "concept", "lang": "en", "question": "What is Big-O notation?", "steps": ["Measures growth with n.", "Keeps dominant term.", "Example: O(n^2)."], "subject": "computer_science", "text": "Answer: Growth-rate bound.\nSteps:\n1. Measures growth with n.\n2. Keeps dominant term.\n3. Example: O(n^2).", "topic": "complexity"}
{"answer": "Nested loops over n each give O(n^2) time.", "choices": {"A": "O(n)", "B": "O(log n)", "C": "O(n^2)", "D": "O(1)"}, "id": "cs_0017", "kind": "multiple_choice", "lang": "en", "question": "Two nested loops over n give what complexity?", "steps": ["Inner runs n per outer.", "Total n x n.", "Select option C."], "subject": "computer_science", "text": "Answer: O(n^2).\nSteps:\n1. Inner runs n per outer.\n2. Total n x n.\n3. Select option C.\nAnswer: (C)", "topic": "complexity"}
{"answer": "A double loop with n = 100 runs 10,000 iterations.", "choices": null, "id": "cs_0018", "kind": "worked_example", "lang": "en", "question": "How many iterations for nested loops with n = 100?", "steps": ["Outer runs 100 times.", "Inner runs 100 each.", "Total = 100 x 100 = 10,000."], "subject": "computer_science", "text": "Answer: 10,000.\nSteps:\n1. Outer runs 100 times.\n2. Inner runs 100 each.\n3. Total = 100 x 100 = 10,000.", "topic": "complexity"}
{"answer": "Časová složitost měří růst doby běhu s velikostí vstupu.", "choices": null, "id": "cs_0019", "kind": "concept", "lang": "cs", "question": "Co je časová složitost?", "steps": ["Závislost na n.", "Zápis O(...).", "Příklad: O(n log n)."], "subject": "computer_science", "text": "Answer: Růst doby s n.\nSteps:\n1. Závislost na n.\n2. Zápis O(...).\n3. Příklad: O(n log n).", "topic": "complexity"}
{"answer": "Linear search best case finds the target first: O(1).", "choices": {"A": "O(n)", "B": "O(log n)", "C": "O(n^2)", "D": "O(1)"}, "id": "cs_0020", "kind": "multiple_choice", "lang": "en", "question": "What is linear search's best case?", "steps": ["Target at index 0.", "One comparison.", "Select option D."], "subject": "computer_science", "text": "Answer: O(1).\nSteps:\n1. Target at index 0.\n2. One comparison.\n3. Select option D.\nAnswer: (D)", "topic": "complexity"}
{"answer": "Worst case bounds the slowest input; average case weights typical inputs.", "choices": null, "id": "cs_0021", "kind": "concept", "lang": "en", "question": "How do worst and average case differ?", "steps": ["Worst: slowest input.", "Average: typical input.", "Quicksort: O(n^2) vs O(n log n)."], "subject": "computer_science", "text": "Answer: Slowest versus typical.\nSteps:\n1. Worst: slowest input.\n2. Average: typical input.\n3. Quicksort: O(n^2) vs O(n log n).", "topic": "complexity"}
{"answer": "Binary search on 1024 items needs at most 10 steps, since log2(1024) = 10.", "choices": null, "id": "cs_0022", "kind": "worked_example", "lang": "en", "question": "How many binary search steps for n = 1024?", "steps": ["Steps = log2(n).", "log2(1024) = 10.", "At most 10 steps."], "subject": "computer_science", "text": "Answer: 10 steps.\nSteps:\n1. Steps = log2(n).\n2. log2(1024) = 10.\n3. At most 10 steps.", "topic": "complexity"}
{"answer": "Dvě vnořené smyčky po 50 dají 2500 operací.", "choices": null, "id": "cs_0023", "kind": "worked_example", "lang": "cs", "question": "Kolik operací mají vnořené smyčky n = 50?", "steps": ["Vnější běží 50krát.", "Vnitřní pokaždé 50krát.", "Celkem 50 x 50 = 2500."], "subject": "computer_science", "text": "Answer: 2500.\nSteps:\n1. Vnější běží 50krát.\n2. Vnitřní pokaždé 50krát.\n3. Celkem 50 x 50 = 2500.", "topic": "complexity"}
{"answer": "O(1) means constant time regardless of input size.", "choices": {"A": "Linear time", "B": "Constant time", "C": "Log time", "D": "Quadratic time"}, "id": "cs_0024", "kind": "multiple_choice", "lang": "en", "question": "What does O(1) mean?", "steps": ["No growth with n.", "Fixed cost.", "Select option B."], "subject": "computer_science", "text": "Answer: Constant time.\nSteps:\n1. No growth with n.\n2. Fixed cost.\n3. Select option B.\nAnswer: (B)", "topic": "complexity"}
{"answer": "Space complexity measures extra memory growth with input size.", "choices": null, "id": "cs_0025", "kind": "concept", "lang": "en", "question": "What is space complexity?", "steps": ["Count extra memory.", "Express in n.", "Example: merge sort O(n)."], "subject": "computer_science", "text": "Answer: Memory growth with n.\nSteps:\n1. Count extra memory.\n2. Express in n.\n3. Example: merge sort O(n).", "topic": "complexity"}
{"answer": "Iterative binary search uses O(1) extra space with two indices.", "choices": null, "id": "cs_0026", "kind": "worked_example", "lang": "en", "question": "What extra space does iterative binary search use?", "steps": ["Only lo/hi indices stored.", "No recursion stack.", "Extra space = O(1)."], "subject": "computer_science", "text": "Answer: O(1).\nSteps:\n1. Only lo/hi indices stored.\n2. No recursion stack.\n3. Extra space = O(1).", "topic": "complexity"}
{"answer": "Bad pivots degrade quicksort to O(n^2) worst case.", "choices": {"A": "O(n)", "B": "O(log n)", "C": "O(n^2)", "D": "O(1)"}, "id": "cs_0027", "kind": "multiple_choice", "lang": "en", "question": "What is quicksort's worst case?", "steps": ["Pivot splits 1 vs n-1.", "Depth becomes n.", "Select option C."], "subject": "computer_science", "text": "Answer: O(n^2).\nSteps:\n1. Pivot splits 1 vs n-1.\n2. Depth becomes n.\n3. Select option C.\nAnswer: (C)", "topic": "complexity"}
{"answer": "Amortizovaná složitost průměruje cenu operací v sekvenci.", "choices": null, "id": "cs_0028", "kind": "concept", "lang": "cs", "question": "Co je amortizovaná složitost?", "steps": ["Drahé operace vzácné.", "Průměr přes sekvenci.", "Příklad: append O(1)."], "subject": "computer_science", "text": "Answer: Průměrná cena v sekvenci.\nSteps:\n1. Drahé operace vzácné.\n2. Průměr přes sekvenci.\n3. Příklad: append O(1).", "topic": "complexity"}
{"answer": "The sum 1..100 is 5050, from 100 x 101 / 2.", "choices": null, "id": "cs_0029", "kind": "worked_example", "lang": "en", "question": "Compute the sum 1 + 2 + ... + 100.", "steps": ["Formula: n(n+1)/2.", "Substitute: 100 x 101/2.", "Sum = 5050."], "subject": "computer_science", "text": "Answer: 5050.\nSteps:\n1. Formula: n(n+1)/2.\n2. Substitute: 100 x 101/2.\n3. Sum = 5050.", "topic": "complexity"}
{"answer": "NP problems verify in polynomial time; P also solves in polynomial time.", "choices": {"A": "Verifiable fast", "B": "Solvable fast", "C": "Unsolvable", "D": "Trivial"}, "id": "cs_0030", "kind": "multiple_choice", "lang": "en", "question": "What defines class NP?", "steps": ["Solutions check quickly.", "Finding may be slow.", "Select option A."], "subject": "computer_science", "text": "Answer: Verifiable fast.\nSteps:\n1. Solutions check quickly.\n2. Finding may be slow.\n3. Select option A.\nAnswer: (A)", "topic": "complexity"}
{"answer": "Arrays index in O(1) but insert slowly; linked lists insert fast but index in O(n).", "choices": null, "id": "cs_0031", "kind": "concept", "lang": "en", "question": "How do arrays and linked lists differ?", "steps": ["Array: contiguous, O(1) index.", "List: nodes, O(n) index.", "List inserts in O(1) given node."], "subject": "computer_science", "text": "Answer: Index speed versus insert speed.\nSteps:\n1. Array: contiguous, O(1) index.\n2. List: nodes, O(n) index.\n3. List inserts in O(1) given node.", "topic": "data_structures"}
{"answer": "Array indexing is O(1) via address arithmetic.", "choices": {"A": "O(n)", "B": "O(1)", "C": "O(log n)", "D": "O(n^2)"}, "id": "cs_0032", "kind": "multiple_choice", "lang": "en", "question": "What is array index access time?", "steps": ["Base plus offset.", "Single step.", "Select option B."], "subject": "computer_science", "text": "Answer: O(1).\nSteps:\n1. Base plus offset.\n2. Single step.\n3. Select option B.\nAnswer: (B)", "topic": "data_structures"}
{"answer": "After pushing 1, 2, 3, pop returns 3 (LIFO).", "choices": null, "id": "cs_0033", "kind": "worked_example", "lang": "en", "question": "Push 1, 2, 3 onto a stack. What does pop return?", "steps": ["Stack top is 3.", "Pop removes top.", "Returns 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Stack top is 3.\n2. Pop removes top.\n3. Returns 3.", "topic": "data_structures"}
{"answer": "Zásobník je LIFO struktura s operacemi push a pop.", "choices": null, "id": "cs_0034", "kind": "concept", "lang": "cs", "question": "Co je zásobník (stack)?", "steps": ["Poslední dovnitř, první ven.", "Operace push a pop.", "Příklad: zásobník volání."], "subject": "computer_science", "text": "Answer: LIFO struktura.\nSteps:\n1. Poslední dovnitř, první ven.\n2. Operace push a pop.\n3. Příklad: zásobník volání.", "topic": "data_structures"}
{"answer": "A queue is FIFO: first in, first out.", "choices": {"A": "FIFO", "B": "LIFO", "C": "LILO", "D": "FILO"}, "id": "cs_0035", "kind": "multiple_choice", "lang": "en", "question": "What order does a queue use?", "steps": ["Enqueue at back.", "Dequeue from front.", "Select option A."], "subject": "computer_science", "text": "Answer: FIFO.\nSteps:\n1. Enqueue at back.\n2. Dequeue from front.\n3. Select option A.\nAnswer: (A)", "topic": "data_structures"}
{"answer": "After enqueueing 1, 2, dequeue returns 1 (FIFO).", "choices": null, "id": "cs_0036", "kind": "worked_example", "lang": "en", "question": "Enqueue 1, 2 into a queue. What does dequeue return?", "steps": ["Front holds 1.", "Dequeue removes front.", "Returns 1."], "subject": "computer_science", "text": "Answer: 1.\nSteps:\n1. Front holds 1.\n2. Dequeue removes front.\n3. Returns 1.", "topic": "data_structures"}
{"answer": "Collisions occur when two keys hash to one slot, fixed by chaining or probing.", "choices": null, "id": "cs_0037", "kind": "concept", "lang": "en", "question": "What is a hash collision?", "steps": ["Two keys, one slot.", "Chain them in a list.", "Or probe next slots."], "subject": "computer_science", "text": "Answer: Two keys, one slot.\nSteps:\n1. Two keys, one slot.\n2. Chain them in a list.\n3. Or probe next slots.", "topic": "data_structures"}
{"answer": "Klíč 7 v tabulce velikosti 5 patří na index 2.", "choices": null, "id": "cs_0038", "kind": "worked_example", "lang": "cs", "question": "Kam patří klíč 7 v hash tabulce velikosti 5?", "steps": ["Spočti 7 mod 5.", "Zbytek je 2.", "Index = 2."], "subject": "computer_science", "text": "Answer: 2.\nSteps:\n1. Spočti 7 mod 5.\n2. Zbytek je 2.\n3. Index = 2.", "topic": "data_structures"}
{"answer": "Balanced BST search averages O(log n).", "choices": {"A": "O(n)", "B": "O(1)", "C": "O(log n)", "D": "O(n^2)"}, "id": "cs_0039", "kind": "multiple_choice", "lang": "en", "question": "What is average BST search time?", "steps": ["Halve tree each step.", "Depth is log n.", "Select option C."], "subject": "computer_science", "text": "Answer: O(log n).\nSteps:\n1. Halve tree each step.\n2. Depth is log n.\n3. Select option C.\nAnswer: (C)", "topic": "data_structures"}
{"answer": "Inorder visits left-root-right; preorder root-first; postorder root-last.", "choices": null, "id": "cs_0040", "kind": "concept", "lang": "en", "question": "What are the tree traversal orders?", "steps": ["Inorder: left, root, right.", "Preorder: root first.", "Postorder: root last."], "subject": "computer_science", "text": "Answer: Inorder, preorder, postorder.\nSteps:\n1. Inorder: left, root, right.\n2. Preorder: root first.\n3. Postorder: root last.", "topic": "data_structures"}
{"answer": "Inorder of root 2 with children 1, 3 gives 1, 2, 3.", "choices": null, "id": "cs_0041", "kind": "worked_example", "lang": "en", "question": "Inorder-traverse root 2, left 1, right 3. What order?", "steps": ["Visit left: 1.", "Visit root: 2.", "Visit right: 3."], "subject": "computer_science", "text": "Answer: 1, 2, 3.\nSteps:\n1. Visit left: 1.\n2. Visit root: 2.\n3. Visit right: 3.", "topic": "data_structures"}
{"answer": "A min-heap root always holds the smallest element.", "choices": {"A": "Largest", "B": "Median", "C": "Random", "D": "Smallest"}, "id": "cs_0042", "kind": "multiple_choice", "lang": "en", "question": "What does a min-heap root hold?", "steps": ["Heap orders by extremum.", "Min-heap keeps min top.", "Select option D."], "subject": "computer_science", "text": "Answer: Smallest.\nSteps:\n1. Heap orders by extremum.\n2. Min-heap keeps min top.\n3. Select option D.\nAnswer: (D)", "topic": "data_structures"}
{"answer": "Fronta je datová struktura FIFO s operacemi enqueue a dequeue.", "choices": null, "id": "cs_0043", "kind": "concept", "lang": "cs", "question": "Co je fronta (queue)?", "steps": ["První dovnitř, první ven.", "Přidávání na konec.", "Odebírání ze začátku."], "subject": "computer_science", "text": "Answer: FIFO struktura.\nSteps:\n1. První dovnitř, první ven.\n2. Přidávání na konec.\n3. Odebírání ze začátku.", "topic": "data_structures"}
{"answer": "Head insertion only rewires one pointer: O(1).", "choices": {"A": "O(1)", "B": "O(n)", "C": "O(log n)", "D": "O(n^2)"}, "id": "cs_0044", "kind": "multiple_choice", "lang": "en", "question": "What is linked-list head insertion time?", "steps": ["Point new node at head.", "Update head.", "Select option A."], "subject": "computer_science", "text": "Answer: O(1).\nSteps:\n1. Point new node at head.\n2. Update head.\n3. Select option A.\nAnswer: (A)", "topic": "data_structures"}
{"answer": "The list 3 -> 5 -> 7 -> None has 3 nodes.", "choices": null, "id": "cs_0045", "kind": "worked_example", "lang": "en", "question": "How many nodes in 3 -> 5 -> 7 -> None?", "steps": ["Count 3.", "Count 5.", "Count 7: total 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Count 3.\n2. Count 5.\n3. Count 7: total 3.", "topic": "data_structures"}
{"answer": "Lists are mutable while tuples are immutable in Python.", "choices": null, "id": "cs_0046", "kind": "concept", "lang": "en", "question": "How do Python lists and tuples differ?", "steps": ["Lists allow item changes.", "Tuples forbid them.", "Both support indexing."], "subject": "computer_science", "text": "Answer: Mutable versus immutable.\nSteps:\n1. Lists allow item changes.\n2. Tuples forbid them.\n3. Both support indexing.", "topic": "python"}
{"answer": "Tuples are immutable; lists, dicts, and sets are mutable.", "choices": {"A": "list", "B": "tuple", "C": "dict", "D": "set"}, "id": "cs_0047", "kind": "multiple_choice", "lang": "en", "question": "Which Python type is immutable?", "steps": ["Lists mutate.", "Dicts and sets mutate.", "Select option B."], "subject": "computer_science", "text": "Answer: tuple.\nSteps:\n1. Lists mutate.\n2. Dicts and sets mutate.\n3. Select option B.\nAnswer: (B)", "topic": "python"}
{"answer": "The comprehension yields [0, 2, 4] by doubling 0, 1, 2.", "choices": null, "id": "cs_0048", "kind": "worked_example", "lang": "en", "question": "What does [x*2 for x in range(3)] produce?", "steps": ["range(3) gives 0, 1, 2.", "Double each: 0, 2, 4.", "Result [0, 2, 4]."], "subject": "computer_science", "text": "Answer: [0, 2, 4].\nSteps:\n1. range(3) gives 0, 1, 2.\n2. Double each: 0, 2, 4.\n3. Result [0, 2, 4].", "topic": "python"}
{"answer": "Seznam je měnitelná posloupnost prvků v hranatých závorkách.", "choices": null, "id": "cs_0049", "kind": "concept", "lang": "cs", "question": "Co je seznam (list) v Pythonu?", "steps": ["Hranaté závorky.", "Prvky lze měnit.", "Indexování od 0."], "subject": "computer_science", "text": "Answer: Měnitelná posloupnost.\nSteps:\n1. Hranaté závorky.\n2. Prvky lze měnit.\n3. Indexování od 0.", "topic": "python"}
{"answer": "len('hello') counts 5 characters.", "choices": {"A": "4", "B": "6", "C": "5", "D": "0"}, "id": "cs_0050", "kind": "multiple_choice", "lang": "en", "question": "What is len('hello')?", "steps": ["Count h,e,l,l,o.", "Total 5.", "Select option C."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. Count h,e,l,l,o.\n2. Total 5.\n3. Select option C.\nAnswer: (C)", "topic": "python"}
{"answer": "dict.get returns the default 0 when the key is missing.", "choices": null, "id": "cs_0051", "kind": "worked_example", "lang": "en", "question": "What does {'a':1}.get('b',0) return?", "steps": ["Key 'b' missing.", "Default 0 applies.", "Returns 0."], "subject": "computer_science", "text": "Answer: 0.\nSteps:\n1. Key 'b' missing.\n2. Default 0 applies.\n3. Returns 0.", "topic": "python"}
{"answer": "Slicing takes [start:stop:step] with stop excluded.", "choices": null, "id": "cs_0052", "kind": "concept", "lang": "en", "question": "How does Python slicing work?", "steps": ["Start included.", "Stop excluded.", "Step skips items."], "subject": "computer_science", "text": "Answer: [start:stop:step].\nSteps:\n1. Start included.\n2. Stop excluded.\n3. Step skips items.", "topic": "python"}
{"answer": "Řez 'abcdef'[1:4] dá 'bcd'.", "choices": null, "id": "cs_0053", "kind": "worked_example", "lang": "cs", "question": "Co vrátí 'abcdef'[1:4]?", "steps": ["Indexy 1 až 3.", "Znaky b, c, d.", "Výsledek 'bcd'."], "subject": "computer_science", "text": "Answer: 'bcd'.\nSteps:\n1. Indexy 1 až 3.\n2. Znaky b, c, d.\n3. Výsledek 'bcd'.", "topic": "python"}
{"answer": "range(3) yields 0, 1, 2.", "choices": {"A": "0, 1, 2", "B": "1, 2, 3", "C": "0, 1, 2, 3", "D": "3, 2, 1"}, "id": "cs_0054", "kind": "multiple_choice", "lang": "en", "question": "What does range(3) produce?", "steps": ["Starts at 0.", "Stops before 3.", "Select option A."], "subject": "computer_science", "text": "Answer: 0, 1, 2.\nSteps:\n1. Starts at 0.\n2. Stops before 3.\n3. Select option A.\nAnswer: (A)", "topic": "python"}
{"answer": "Functions are defined with def and send values back via return.", "choices": null, "id": "cs_0055", "kind": "concept", "lang": "en", "question": "How are Python functions defined?", "steps": ["Use def keyword.", "Name parameters.", "Return the result."], "subject": "computer_science", "text": "Answer: def with return.\nSteps:\n1. Use def keyword.\n2. Name parameters.\n3. Return the result.", "topic": "python"}
{"answer": "f(3) = 3**2 + 1 = 10.", "choices": null, "id": "cs_0056", "kind": "worked_example", "lang": "en", "question": "If f(x) = x**2 + 1, what is f(3)?", "steps": ["Square: 3**2 = 9.", "Add 1.", "Result = 10."], "subject": "computer_science", "text": "Answer: 10.\nSteps:\n1. Square: 3**2 = 9.\n2. Add 1.\n3. Result = 10.", "topic": "python"}
{"answer": "The def keyword defines a Python function.", "choices": {"A": "fun", "B": "function", "C": "define", "D": "def"}, "id": "cs_0057", "kind": "multiple_choice", "lang": "en", "question": "Which keyword defines a function?", "steps": ["Python uses def.", "Others are wrong.", "Select option D."], "subject": "computer_science", "text": "Answer: def.\nSteps:\n1. Python uses def.\n2. Others are wrong.\n3. Select option D.\nAnswer: (D)", "topic": "python"}
{"answer": "Slovník mapuje klíče na hodnoty ve složených závorkách.", "choices": null, "id": "cs_0058", "kind": "concept", "lang": "cs", "question": "Co je slovník (dict)?", "steps": ["Páry klíč: hodnota.", "Složené závorky.", "Přístup přes klíč."], "subject": "computer_science", "text": "Answer: Mapování klíčů.\nSteps:\n1. Páry klíč: hodnota.\n2. Složené závorky.\n3. Přístup přes klíč.", "topic": "python"}
{"answer": "The average is 2.5, from 10 divided by 4.", "choices": null, "id": "cs_0059", "kind": "worked_example", "lang": "en", "question": "What is sum([1,2,3,4])/4?", "steps": ["Sum = 10.", "Divide by 4.", "Result = 2.5."], "subject": "computer_science", "text": "Answer: 2.5.\nSteps:\n1. Sum = 10.\n2. Divide by 4.\n3. Result = 2.5.", "topic": "python"}
{"answer": "'a' in 'cat' is True since 'a' appears in the string.", "choices": {"A": "Error", "B": "True", "C": "False", "D": "None"}, "id": "cs_0060", "kind": "multiple_choice", "lang": "en", "question": "What is 'a' in 'cat'?", "steps": ["Check membership.", "'a' is present.", "Select option B."], "subject": "computer_science", "text": "Answer: True.\nSteps:\n1. Check membership.\n2. 'a' is present.\n3. Select option B.\nAnswer: (B)", "topic": "python"}
{"answer": "let allows reassignment, const forbids it, and var is legacy function-scoped.", "choices": null, "id": "cs_0061", "kind": "concept", "lang": "en", "question": "How do let, const, and var differ?", "steps": ["let: block-scoped, mutable.", "const: no reassignment.", "var: legacy, function-scoped."], "subject": "computer_science", "text": "Answer: Mutable, fixed, legacy.\nSteps:\n1. let: block-scoped, mutable.\n2. const: no reassignment.\n3. var: legacy, function-scoped.", "topic": "javascript"}
{"answer": "const forbids rebinding the variable to a new value.", "choices": {"A": "Allows anything", "B": "Makes objects frozen", "C": "Forbids reassignment", "D": "Deletes variables"}, "id": "cs_0062", "kind": "multiple_choice", "lang": "en", "question": "What does const prevent?", "steps": ["Binding stays fixed.", "Contents may mutate.", "Select option C."], "subject": "computer_science", "text": "Answer: Forbids reassignment.\nSteps:\n1. Binding stays fixed.\n2. Contents may mutate.\n3. Select option C.\nAnswer: (C)", "topic": "javascript"}
{"answer": "map doubles each element, giving [2, 4, 6].", "choices": null, "id": "cs_0063", "kind": "worked_example", "lang": "en", "question": "What does [1,2,3].map(x => x*2) return?", "steps": ["Apply x*2 to 1: 2.", "To 2: 4; to 3: 6.", "Result [2, 4, 6]."], "subject": "computer_science", "text": "Answer: [2, 4, 6].\nSteps:\n1. Apply x*2 to 1: 2.\n2. To 2: 4; to 3: 6.\n3. Result [2, 4, 6].", "topic": "javascript"}
{"answer": "Pole je seřazená kolekce prvků v hranatých závorkách.", "choices": null, "id": "cs_0064", "kind": "concept", "lang": "cs", "question": "Co je pole v JavaScriptu?", "steps": ["Hranaté závorky.", "Indexování od 0.", "Metody map, filter."], "subject": "computer_science", "text": "Answer: Seřazená kolekce.\nSteps:\n1. Hranaté závorky.\n2. Indexování od 0.\n3. Metody map, filter.", "topic": "javascript"}
{"answer": "'hello'.length counts 5 characters.", "choices": null, "id": "cs_0065", "kind": "worked_example", "lang": "en", "question": "What is 'hello'.length?", "steps": ["Count h,e,l,l,o.", "Total 5.", "length = 5."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. Count h,e,l,l,o.\n2. Total 5.\n3. length = 5.", "topic": "javascript"}
{"answer": "Strict === compares value and type without coercion.", "choices": {"A": "Value and type", "B": "Value only", "C": "Type only", "D": "Nothing"}, "id": "cs_0066", "kind": "multiple_choice", "lang": "en", "question": "What does === check?", "steps": ["No type coercion.", "Both must match.", "Select option A."], "subject": "computer_science", "text": "Answer: Value and type.\nSteps:\n1. No type coercion.\n2. Both must match.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "Arrow functions are compact (x) => expr with lexical this.", "choices": null, "id": "cs_0067", "kind": "concept", "lang": "en", "question": "What are arrow functions?", "steps": ["Short syntax.", "Lexical this binding.", "Example: x => x*2."], "subject": "computer_science", "text": "Answer: Compact lexical functions.\nSteps:\n1. Short syntax.\n2. Lexical this binding.\n3. Example: x => x*2.", "topic": "javascript"}
{"answer": "Filtr vrátí [2, 3], prvky větší než 1.", "choices": null, "id": "cs_0068", "kind": "worked_example", "lang": "cs", "question": "Co vrátí [1,2,3].filter(x => x > 1)?", "steps": ["Testuj 1: ne.", "Testuj 2, 3: ano.", "Výsledek [2, 3]."], "subject": "computer_science", "text": "Answer: [2, 3].\nSteps:\n1. Testuj 1: ne.\n2. Testuj 2, 3: ano.\n3. Výsledek [2, 3].", "topic": "javascript"}
{"answer": "JSON.parse converts a JSON string into an object.", "choices": {"A": "Object to string", "B": "Number to string", "C": "Array to set", "D": "String to object"}, "id": "cs_0069", "kind": "multiple_choice", "lang": "en", "question": "What does JSON.parse do?", "steps": ["Takes JSON text.", "Builds value.", "Select option D."], "subject": "computer_science", "text": "Answer: String to object.\nSteps:\n1. Takes JSON text.\n2. Builds value.\n3. Select option D.\nAnswer: (D)", "topic": "javascript"}
{"answer": "Promises represent future values with then/catch chains instead of nested callbacks.", "choices": null, "id": "cs_0070", "kind": "concept", "lang": "en", "question": "What are promises?", "steps": ["Pending, then settled.", "then handles success.", "catch handles errors."], "subject": "computer_science", "text": "Answer: Future values with chains.\nSteps:\n1. Pending, then settled.\n2. then handles success.\n3. catch handles errors.", "topic": "javascript"}
{"answer": "2 + '2' coerces to string concatenation, giving '22'.", "choices": null, "id": "cs_0071", "kind": "worked_example", "lang": "en", "question": "What is 2 + '2' in JavaScript?", "steps": ["One operand is string.", "Number coerces to '2'.", "Concat gives '22'."], "subject": "computer_science", "text": "Answer: '22'.\nSteps:\n1. One operand is string.\n2. Number coerces to '2'.\n3. Concat gives '22'.", "topic": "javascript"}
{"answer": "Object literals group key-value pairs in braces.", "choices": null, "id": "cs_0072", "kind": "concept", "lang": "en", "question": "What are object literals?", "steps": ["Braces hold pairs.", "Keys map to values.", "Example: {a: 1}."], "subject": "computer_science", "text": "Answer: Key-value in braces.\nSteps:\n1. Braces hold pairs.\n2. Keys map to values.\n3. Example: {a: 1}.", "topic": "javascript"}
{"answer": "Arrays are objects, so typeof [] is 'object'.", "choices": {"A": "array", "B": "object", "C": "list", "D": "undefined"}, "id": "cs_0073", "kind": "multiple_choice", "lang": "en", "question": "What is typeof []?", "steps": ["Arrays inherit objects.", "typeof reports object.", "Select option B."], "subject": "computer_science", "text": "Answer: 'object'.\nSteps:\n1. Arrays inherit objects.\n2. typeof reports object.\n3. Select option B.\nAnswer: (B)", "topic": "javascript"}
{"answer": "Math.max(3, 7, 5) vrátí 7.", "choices": null, "id": "cs_0074", "kind": "worked_example", "lang": "cs", "question": "Co vrátí Math.max(3, 7, 5)?", "steps": ["Porovnej 3 a 7.", "Větší je 7.", "Proti 5 vítězí 7."], "subject": "computer_science", "text": "Answer: 7.\nSteps:\n1. Porovnej 3 a 7.\n2. Větší je 7.\n3. Proti 5 vítězí 7.", "topic": "javascript"}
{"answer": "Template literals use backticks with ${} interpolation.", "choices": null, "id": "cs_0075", "kind": "concept", "lang": "en", "question": "What are template literals?", "steps": ["Backtick strings.", "Embed ${expr}.", "Span multiple lines."], "subject": "computer_science", "text": "Answer: Backtick interpolated strings.\nSteps:\n1. Backtick strings.\n2. Embed ${expr}.\n3. Span multiple lines.", "topic": "javascript"}
{"answer": "SELECT lists columns from a table, optionally filtered and ordered.", "choices": null, "id": "cs_0076", "kind": "concept", "lang": "en", "question": "What does SELECT do in SQL?", "steps": ["Names columns.", "Names table.", "Adds filters."], "subject": "computer_science", "text": "Answer: Reads columns from table.\nSteps:\n1. Names columns.\n2. Names table.\n3. Adds filters.", "topic": "sql"}
{"answer": "WHERE filters rows by a condition.", "choices": {"A": "WHERE", "B": "ORDER", "C": "GROUP", "D": "JOIN"}, "id": "cs_0077", "kind": "multiple_choice", "lang": "en", "question": "Which clause filters rows?", "steps": ["Need row condition.", "That is WHERE.", "Select option A."], "subject": "computer_science", "text": "Answer: WHERE.\nSteps:\n1. Need row condition.\n2. That is WHERE.\n3. Select option A.\nAnswer: (A)", "topic": "sql"}
{"answer": "SELECT 2 + 3 returns 5.", "choices": null, "id": "cs_0078", "kind": "worked_example", "lang": "en", "question": "What does SELECT 2 + 3 return?", "steps": ["Add 2 and 3.", "Result 5.", "One row returned."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. Add 2 and 3.\n2. Result 5.\n3. One row returned.", "topic": "sql"}
{"answer": "SELECT čte sloupce z tabulky, volitelně s filtrem.", "choices": null, "id": "cs_0079", "kind": "concept", "lang": "cs", "question": "Co je dotaz SELECT?", "steps": ["Jmenuje sloupce.", "Jmenuje tabulku.", "Přidá filtr."], "subject": "computer_science", "text": "Answer: Čtení z tabulky.\nSteps:\n1. Jmenuje sloupce.\n2. Jmenuje tabulku.\n3. Přidá filtr.", "topic": "sql"}
{"answer": "COUNT(*) over 4 rows returns 4.", "choices": null, "id": "cs_0080", "kind": "worked_example", "lang": "en", "question": "Table t has 4 rows. What does SELECT COUNT(*) FROM t return?", "steps": ["Count all rows.", "Four present.", "Returns 4."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Count all rows.\n2. Four present.\n3. Returns 4.", "topic": "sql"}
{"answer": "ORDER BY sorts result rows by columns.", "choices": {"A": "WHERE", "B": "GROUP BY", "C": "ORDER BY", "D": "HAVING"}, "id": "cs_0081", "kind": "multiple_choice", "lang": "en", "question": "Which clause sorts results?", "steps": ["Need ordering.", "That is ORDER BY.", "Select option C."], "subject": "computer_science", "text": "Answer: ORDER BY.\nSteps:\n1. Need ordering.\n2. That is ORDER BY.\n3. Select option C.\nAnswer: (C)", "topic": "sql"}
{"answer": "INNER keeps matches, LEFT keeps all left rows, FULL keeps everything.", "choices": null, "id": "cs_0082", "kind": "concept", "lang": "en", "question": "How do JOIN types differ?", "steps": ["INNER: matches only.", "LEFT: all left rows.", "FULL: all rows both."], "subject": "computer_science", "text": "Answer: Match scope differs.\nSteps:\n1. INNER: matches only.\n2. LEFT: all left rows.\n3. FULL: all rows both.", "topic": "sql"}
{"answer": "SELECT 10.0 / 4 vrátí 2.5.", "choices": null, "id": "cs_0083", "kind": "worked_example", "lang": "cs", "question": "Co vrátí SELECT 10.0 / 4?", "steps": ["Vyděl 10.0 čtyřmi.", "Výsledek 2.5.", "Jeden řádek."], "subject": "computer_science", "text": "Answer: 2.5.\nSteps:\n1. Vyděl 10.0 čtyřmi.\n2. Výsledek 2.5.\n3. Jeden řádek.", "topic": "sql"}
{"answer": "DISTINCT drops duplicate rows from results.", "choices": {"A": "UNIQUE", "B": "DISTINCT", "C": "FILTER", "D": "LIMIT"}, "id": "cs_0084", "kind": "multiple_choice", "lang": "en", "question": "Which keyword removes duplicates?", "steps": ["Need dedup.", "That is DISTINCT.", "Select option B."], "subject": "computer_science", "text": "Answer: DISTINCT.\nSteps:\n1. Need dedup.\n2. That is DISTINCT.\n3. Select option B.\nAnswer: (B)", "topic": "sql"}
{"answer": "GROUP BY aggregates per group; HAVING filters groups like WHERE filters rows.", "choices": null, "id": "cs_0085", "kind": "concept", "lang": "en", "question": "How do GROUP BY and HAVING work?", "steps": ["Group rows by key.", "Aggregate each group.", "HAVING filters groups."], "subject": "computer_science", "text": "Answer: Aggregate then filter groups.\nSteps:\n1. Group rows by key.\n2. Aggregate each group.\n3. HAVING filters groups.", "topic": "sql"}
{"answer": "SUM(1, 2, 3) totals 6.", "choices": null, "id": "cs_0086", "kind": "worked_example", "lang": "en", "question": "What does SELECT SUM(x) give for x in (1,2,3)?", "steps": ["Add 1 + 2 + 3.", "Total 6.", "One row returned."], "subject": "computer_science", "text": "Answer: 6.\nSteps:\n1. Add 1 + 2 + 3.\n2. Total 6.\n3. One row returned.", "topic": "sql"}
{"answer": "A primary key uniquely identifies each row and cannot be NULL.", "choices": null, "id": "cs_0087", "kind": "concept", "lang": "en", "question": "What is a primary key?", "steps": ["Unique per row.", "Never NULL.", "Example: id column."], "subject": "computer_science", "text": "Answer: Unique row identifier.\nSteps:\n1. Unique per row.\n2. Never NULL.\n3. Example: id column.", "topic": "sql"}
{"answer": "PRIMARY KEY enforces unique non-null row identity.", "choices": {"A": "FOREIGN KEY", "B": "INDEX", "C": "NULL", "D": "PRIMARY KEY"}, "id": "cs_0088", "kind": "multiple_choice", "lang": "en", "question": "Which constraint gives unique row identity?", "steps": ["Need unique id.", "That is PRIMARY KEY.", "Select option D."], "subject": "computer_science", "text": "Answer: PRIMARY KEY.\nSteps:\n1. Need unique id.\n2. That is PRIMARY KEY.\n3. Select option D.\nAnswer: (D)", "topic": "sql"}
{"answer": "Primární klíč jednoznačně určuje každý řádek a není NULL.", "choices": null, "id": "cs_0089", "kind": "concept", "lang": "cs", "question": "Co je primární klíč?", "steps": ["Jedinečný na řádek.", "Nikdy NULL.", "Příklad: sloupec id."], "subject": "computer_science", "text": "Answer: Jedinečný identifikátor.\nSteps:\n1. Jedinečný na řádek.\n2. Nikdy NULL.\n3. Příklad: sloupec id.", "topic": "sql"}
{"answer": "AVG(10, 20, 30) = 60/3 = 20.0.", "choices": null, "id": "cs_0090", "kind": "worked_example", "lang": "en", "question": "What does SELECT AVG(x) give for x in (10,20,30)?", "steps": ["Sum = 60.", "Count = 3.", "Average = 20.0."], "subject": "computer_science", "text": "Answer: 20.0.\nSteps:\n1. Sum = 60.\n2. Count = 3.\n3. Average = 20.0.", "topic": "sql"}
{"answer": "TCP guarantees ordered delivery; UDP is fast but unreliable.", "choices": null, "id": "cs_0091", "kind": "concept", "lang": "en", "question": "How do TCP and UDP differ?", "steps": ["TCP: reliable, ordered.", "UDP: fast, best-effort.", "Use: web vs video."], "subject": "computer_science", "text": "Answer: Reliable versus fast.\nSteps:\n1. TCP: reliable, ordered.\n2. UDP: fast, best-effort.\n3. Use: web vs video.", "topic": "networking"}
{"answer": "TCP retransmits lost packets for reliability.", "choices": {"A": "TCP", "B": "UDP", "C": "IP", "D": "ICMP"}, "id": "cs_0092", "kind": "multiple_choice", "lang": "en", "question": "Which protocol is reliable?", "steps": ["Needs retransmission.", "TCP provides it.", "Select option A."], "subject": "computer_science", "text": "Answer: TCP.\nSteps:\n1. Needs retransmission.\n2. TCP provides it.\n3. Select option A.\nAnswer: (A)", "topic": "networking"}
{"answer": "A /24 network holds 254 usable hosts (2^8 - 2).", "choices": null, "id": "cs_0093", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in 192.168.1.0/24?", "steps": ["Host bits = 32 - 24 = 8.", "Total = 2^8 = 256.", "Minus network/broadcast = 254."], "subject": "computer_science", "text": "Answer: 254.\nSteps:\n1. Host bits = 32 - 24 = 8.\n2. Total = 2^8 = 256.\n3. Minus network/broadcast = 254.", "topic": "networking"}
{"answer": "IP adresa je číselný identifikátor zařízení v síti.", "choices": null, "id": "cs_0094", "kind": "concept", "lang": "cs", "question": "Co je IP adresa?", "steps": ["Číselný identifikátor.", "IPv4 má 32 bitů.", "Příklad: 192.168.1.1."], "subject": "computer_science", "text": "Answer: Identifikátor zařízení.\nSteps:\n1. Číselný identifikátor.\n2. IPv4 má 32 bitů.\n3. Příklad: 192.168.1.1.", "topic": "networking"}
{"answer": "DNS resolves domain names to IP addresses via hierarchical lookup.", "choices": null, "id": "cs_0095", "kind": "concept", "lang": "en", "question": "How does DNS resolution work?", "steps": ["Query resolver.", "Walk root to TLD to auth.", "Cache the answer."], "subject": "computer_science", "text": "Answer: Names to IPs hierarchically.\nSteps:\n1. Query resolver.\n2. Walk root to TLD to auth.\n3. Cache the answer.", "topic": "networking"}
{"answer": "DNS maps domain names to IP addresses.", "choices": {"A": "IPs to MACs", "B": "Names to IPs", "C": "Ports to apps", "D": "Files to URLs"}, "id": "cs_0096", "kind": "multiple_choice", "lang": "en", "question": "What does DNS map?", "steps": ["Names in, IPs out.", "Eliminate others.", "Select option B."], "subject": "computer_science", "text": "Answer: Names to IPs.\nSteps:\n1. Names in, IPs out.\n2. Eliminate others.\n3. Select option B.\nAnswer: (B)", "topic": "networking"}
{"answer": "A /16 holds 65,534 usable hosts (2^16 - 2).", "choices": null, "id": "cs_0097", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in a /16 network?", "steps": ["Host bits = 16.", "Total = 2^16 = 65,536.", "Minus 2 = 65,534."], "subject": "computer_science", "text": "Answer: 65,534.\nSteps:\n1. Host bits = 16.\n2. Total = 2^16 = 65,536.\n3. Minus 2 = 65,534.", "topic": "networking"}
{"answer": "HTTP standardně používá port 80.", "choices": null, "id": "cs_0098", "kind": "worked_example", "lang": "cs", "question": "Kolik je standardní port HTTP?", "steps": ["HTTP má 80.", "HTTPS má 443.", "Odpověď: 80."], "subject": "computer_science", "text": "Answer: 80.\nSteps:\n1. HTTP má 80.\n2. HTTPS má 443.\n3. Odpověď: 80.", "topic": "networking"}
{"answer": "HTTP defaults to port 80.", "choices": {"A": "21", "B": "25", "C": "80", "D": "443"}, "id": "cs_0099", "kind": "multiple_choice", "lang": "en", "question": "What is the default HTTP port?", "steps": ["HTTP standard.", "Port 80.", "Select option C."], "subject": "computer_science", "text": "Answer: 80.\nSteps:\n1. HTTP standard.\n2. Port 80.\n3. Select option C.\nAnswer: (C)", "topic": "networking"}
{"answer": "The OSI model has 7 layers from physical to application.", "choices": null, "id": "cs_0100", "kind": "concept", "lang": "en", "question": "How many OSI layers exist?", "steps": ["Physical to application.", "Seven total.", "Example: network is 3."], "subject": "computer_science", "text": "Answer: 7 layers.\nSteps:\n1. Physical to application.\n2. Seven total.\n3. Example: network is 3.", "topic": "networking"}
{"answer": "A /24 mask is 255.255.255.0: 24 ones then 8 zeros.", "choices": null, "id": "cs_0101", "kind": "worked_example", "lang": "en", "question": "What is the subnet mask for /24?", "steps": ["24 network bits set.", "Three full octets.", "Mask = 255.255.255.0."], "subject": "computer_science", "text": "Answer: 255.255.255.0.\nSteps:\n1. 24 network bits set.\n2. Three full octets.\n3. Mask = 255.255.255.0.", "topic": "networking"}
{"answer": "HTTPS defaults to port 443.", "choices": {"A": "80", "B": "21", "C": "25", "D": "443"}, "id": "cs_0102", "kind": "multiple_choice", "lang": "en", "question": "What is the default HTTPS port?", "steps": ["Encrypted HTTP.", "Port 443.", "Select option D."], "subject": "computer_science", "text": "Answer: 443.\nSteps:\n1. Encrypted HTTP.\n2. Port 443.\n3. Select option D.\nAnswer: (D)", "topic": "networking"}
{"answer": "DNS převádí doménová jména na IP adresy.", "choices": null, "id": "cs_0103", "kind": "concept", "lang": "cs", "question": "Co je DNS?", "steps": ["Jména na adresy.", "Hierarchické dotazy.", "Ukládání do mezipaměti."], "subject": "computer_science", "text": "Answer: Překlad jmen na IP.\nSteps:\n1. Jména na adresy.\n2. Hierarchické dotazy.\n3. Ukládání do mezipaměti.", "topic": "networking"}
{"answer": "Switches forward within a LAN by MAC; routers join networks by IP.", "choices": null, "id": "cs_0104", "kind": "concept", "lang": "en", "question": "How do routers and switches differ?", "steps": ["Switch: LAN, MAC-based.", "Router: networks, IP-based.", "Layers 2 vs 3."], "subject": "computer_science", "text": "Answer: LAN versus networks.\nSteps:\n1. Switch: LAN, MAC-based.\n2. Router: networks, IP-based.\n3. Layers 2 vs 3.", "topic": "networking"}
{"answer": "192.168.1.1 is private; the rest are public addresses.", "choices": {"A": "192.168.1.1", "B": "8.8.8.8", "C": "1.1.1.1", "D": "9.9.9.9"}, "id": "cs_0105", "kind": "multiple_choice", "lang": "en", "question": "Which IP is private?", "steps": ["192.168.x is private.", "Others are public.", "Select option A."], "subject": "computer_science", "text": "Answer: 192.168.1.1.\nSteps:\n1. 192.168.x is private.\n2. Others are public.\n3. Select option A.\nAnswer: (A)", "topic": "networking"}
{"answer": "The relational model stores data in tables of rows and columns.", "choices": null, "id": "cs_0106", "kind": "concept", "lang": "en", "question": "What is the relational model?", "steps": ["Tables hold data.", "Rows are records.", "Keys link tables."], "subject": "computer_science", "text": "Answer: Tables of rows.\nSteps:\n1. Tables hold data.\n2. Rows are records.\n3. Keys link tables.", "topic": "databases"}
{"answer": "Table rows are also called records.", "choices": {"A": "Attributes", "B": "Records", "C": "Schemas", "D": "Keys"}, "id": "cs_0107", "kind": "multiple_choice", "lang": "en", "question": "What are table rows also called?", "steps": ["Rows hold one entry.", "Called records.", "Select option B."], "subject": "computer_science", "text": "Answer: Records.\nSteps:\n1. Rows hold one entry.\n2. Called records.\n3. Select option B.\nAnswer: (B)", "topic": "databases"}
{"answer": "Three INSERTs into an empty table leave 3 rows.", "choices": null, "id": "cs_0108", "kind": "worked_example", "lang": "en", "question": "INSERT 3 rows into an empty table. How many rows?", "steps": ["Start at 0.", "Add 3.", "Total = 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Start at 0.\n2. Add 3.\n3. Total = 3.", "topic": "databases"}
{"answer": "Relační databáze ukládá data do tabulek propojených klíči.", "choices": null, "id": "cs_0109", "kind": "concept", "lang": "cs", "question": "Co je relační databáze?", "steps": ["Tabulky řádků.", "Sloupce atributů.", "Klíče spojují."], "subject": "computer_science", "text": "Answer: Tabulky s klíči.\nSteps:\n1. Tabulky řádků.\n2. Sloupce atributů.\n3. Klíče spojují.", "topic": "databases"}
{"answer": "Indexes speed lookups by avoiding full table scans.", "choices": null, "id": "cs_0110", "kind": "concept", "lang": "en", "question": "What is a database index?", "steps": ["Sorted lookup aid.", "Skips full scans.", "Costs write speed."], "subject": "computer_science", "text": "Answer: Fast lookup aid.\nSteps:\n1. Sorted lookup aid.\n2. Skips full scans.\n3. Costs write speed.", "topic": "databases"}
{"answer": "Indexes exist to make lookups faster.", "choices": {"A": "Faster lookup", "B": "Slower reads", "C": "More storage only", "D": "No effect"}, "id": "cs_0111", "kind": "multiple_choice", "lang": "en", "question": "What is an index for?", "steps": ["Avoid full scans.", "Speed queries.", "Select option A."], "subject": "computer_science", "text": "Answer: Faster lookup.\nSteps:\n1. Avoid full scans.\n2. Speed queries.\n3. Select option A.\nAnswer: (A)", "topic": "databases"}
{"answer": "A cross join of 3 and 4 rows yields at most 12 rows.", "choices": null, "id": "cs_0112", "kind": "worked_example", "lang": "en", "question": "Cross-join tables of 3 and 4 rows. How many rows max?", "steps": ["Each left pairs each right.", "Multiply: 3 x 4.", "Max = 12."], "subject": "computer_science", "text": "Answer: 12.\nSteps:\n1. Each left pairs each right.\n2. Multiply: 3 x 4.\n3. Max = 12.", "topic": "databases"}
{"answer": "Po smazání 1 ze 3 řádků zbudou 2.", "choices": null, "id": "cs_0113", "kind": "worked_example", "lang": "cs", "question": "Tabulka má 3 řádky, DELETE smaže 1. Kolik zbude?", "steps": ["Začni na 3.", "Odečti 1.", "Zbývají 2."], "subject": "computer_science", "text": "Answer: 2.\nSteps:\n1. Začni na 3.\n2. Odečti 1.\n3. Zbývají 2.", "topic": "databases"}
{"answer": "ACID stands for atomicity, consistency, isolation, durability.", "choices": {"A": "Availability", "B": "Accuracy", "C": "Atomicity", "D": "Audit"}, "id": "cs_0114", "kind": "multiple_choice", "lang": "en", "question": "What is the A in ACID?", "steps": ["All-or-nothing.", "That is atomicity.", "Select option C."], "subject": "computer_science", "text": "Answer: Atomicity.\nSteps:\n1. All-or-nothing.\n2. That is atomicity.\n3. Select option C.\nAnswer: (C)", "topic": "databases"}
{"answer": "A transaction groups statements into one atomic unit.", "choices": null, "id": "cs_0115", "kind": "concept", "lang": "en", "question": "What is a transaction?", "steps": ["Group statements.", "Commit or rollback.", "Stays atomic."], "subject": "computer_science", "text": "Answer: Atomic statement group.\nSteps:\n1. Group statements.\n2. Commit or rollback.\n3. Stays atomic.", "topic": "databases"}
{"answer": "Raising 100 by 10% gives 110.", "choices": null, "id": "cs_0116", "kind": "worked_example", "lang": "en", "question": "UPDATE sets price = price * 1.1 with price 100. New value?", "steps": ["Multiply: 100 x 1.1.", "Result 110.", "One row updated."], "subject": "computer_science", "text": "Answer: 110.\nSteps:\n1. Multiply: 100 x 1.1.\n2. Result 110.\n3. One row updated.", "topic": "databases"}
{"answer": "A foreign key references another table's primary key.", "choices": null, "id": "cs_0117", "kind": "concept", "lang": "en", "question": "What is a foreign key?", "steps": ["Points to other table.", "Matches its PK.", "Enforces links."], "subject": "computer_science", "text": "Answer: Link to other PK.\nSteps:\n1. Points to other table.\n2. Matches its PK.\n3. Enforces links.", "topic": "databases"}
{"answer": "Foreign keys reference another table's primary key.", "choices": {"A": "Own index", "B": "Another table's PK", "C": "Any column", "D": "Nothing"}, "id": "cs_0118", "kind": "multiple_choice", "lang": "en", "question": "What does a foreign key reference?", "steps": ["Links tables.", "Targets PK.", "Select option B."], "subject": "computer_science", "text": "Answer: Another table's PK.\nSteps:\n1. Links tables.\n2. Targets PK.\n3. Select option B.\nAnswer: (B)", "topic": "databases"}
{"answer": "Transakce je atomická skupina příkazů s commitem nebo rollbackem.", "choices": null, "id": "cs_0119", "kind": "concept", "lang": "cs", "question": "Co je transakce?", "steps": ["Skupina příkazů.", "Commit nebo rollback.", "Vše nebo nic."], "subject": "computer_science", "text": "Answer: Atomická skupina.\nSteps:\n1. Skupina příkazů.\n2. Commit nebo rollback.\n3. Vše nebo nic.", "topic": "databases"}
{"answer": "The query returns the 2 matching rows.", "choices": null, "id": "cs_0120", "kind": "worked_example", "lang": "en", "question": "5 rows exist, WHERE matches 2. How many returned?", "steps": ["Filter 5 rows.", "Keep 2.", "Returns 2."], "subject": "computer_science", "text": "Answer: 2.\nSteps:\n1. Filter 5 rows.\n2. Keep 2.\n3. Returns 2.", "topic": "databases"}
{"answer": "A process owns memory; threads share it while running code.", "choices": null, "id": "cs_0121", "kind": "concept", "lang": "en", "question": "How do processes and threads differ?", "steps": ["Process: own memory.", "Thread: shared memory.", "Threads run inside processes."], "subject": "computer_science", "text": "Answer: Own versus shared memory.\nSteps:\n1. Process: own memory.\n2. Thread: shared memory.\n3. Threads run inside processes.", "topic": "operating_systems"}
{"answer": "A thread is the lightweight unit of execution.", "choices": {"A": "Process", "B": "Program", "C": "File", "D": "Thread"}, "id": "cs_0122", "kind": "multiple_choice", "lang": "en", "question": "What is the lightweight execution unit?", "steps": ["Runs code.", "Shares memory.", "Select option D."], "subject": "computer_science", "text": "Answer: Thread.\nSteps:\n1. Runs code.\n2. Shares memory.\n3. Select option D.\nAnswer: (D)", "topic": "operating_systems"}
{"answer": "4 cores with 2 threads each give 8 logical CPUs.", "choices": null, "id": "cs_0123", "kind": "worked_example", "lang": "en", "question": "4 cores, 2 threads each. How many logical CPUs?", "steps": ["Multiply: 4 x 2.", "Result 8.", "8 logical CPUs."], "subject": "computer_science", "text": "Answer: 8.\nSteps:\n1. Multiply: 4 x 2.\n2. Result 8.\n3. 8 logical CPUs.", "topic": "operating_systems"}
{"answer": "Proces je běžící program s vlastním paměťovým prostorem.", "choices": null, "id": "cs_0124", "kind": "concept", "lang": "cs", "question": "Co je proces?", "steps": ["Běžící program.", "Vlastní paměť.", "Spravuje ho OS."], "subject": "computer_science", "text": "Answer: Běžící program.\nSteps:\n1. Běžící program.\n2. Vlastní paměť.\n3. Spravuje ho OS.", "topic": "operating_systems"}
{"answer": "Paging splits memory into fixed pages swapped between RAM and disk.", "choices": null, "id": "cs_0125", "kind": "concept", "lang": "en", "question": "What is virtual memory paging?", "steps": ["Fixed-size pages.", "Swap RAM to disk.", "Illusion of more RAM."], "subject": "computer_science", "text": "Answer: Page swapping illusion.\nSteps:\n1. Fixed-size pages.\n2. Swap RAM to disk.\n3. Illusion of more RAM.", "topic": "operating_systems"}
{"answer": "FIFO evicts the oldest loaded page first.", "choices": {"A": "Oldest", "B": "Newest", "C": "Random", "D": "Largest"}, "id": "cs_0126", "kind": "multiple_choice", "lang": "en", "question": "Which page does FIFO evict?", "steps": ["First in first out.", "Oldest leaves.", "Select option A."], "subject": "computer_science", "text": "Answer: Oldest.\nSteps:\n1. First in first out.\n2. Oldest leaves.\n3. Select option A.\nAnswer: (A)", "topic": "operating_systems"}
{"answer": "Three fresh references with 3 frames cause 3 page faults.", "choices": null, "id": "cs_0127", "kind": "worked_example", "lang": "en", "question": "3 frames empty, references 1, 2, 3. How many faults?", "steps": ["1 misses: fault.", "2 misses: fault.", "3 misses: fault; total 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. 1 misses: fault.\n2. 2 misses: fault.\n3. 3 misses: fault; total 3.", "topic": "operating_systems"}
{"answer": "2 GB RAM plus 1 GB swap dá 3 GB virtuální paměti.", "choices": null, "id": "cs_0128", "kind": "worked_example", "lang": "cs", "question": "2 GB RAM a 1 GB swap. Kolik virtuální paměti?", "steps": ["Sečti RAM a swap.", "2 + 1.", "Celkem 3 GB."], "subject": "computer_science", "text": "Answer: 3 GB.\nSteps:\n1. Sečti RAM a swap.\n2. 2 + 1.\n3. Celkem 3 GB.", "topic": "operating_systems"}
{"answer": "Deadlock needs all four Coffman conditions at once.", "choices": {"A": "2", "B": "3", "C": "4", "D": "1"}, "id": "cs_0129", "kind": "multiple_choice", "lang": "en", "question": "How many conditions does deadlock need?", "steps": ["Mutual exclusion etc.", "Four total.", "Select option C."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Mutual exclusion etc.\n2. Four total.\n3. Select option C.\nAnswer: (C)", "topic": "operating_systems"}
{"answer": "Round-robin cycles processes with fixed time quanta.", "choices": null, "id": "cs_0130", "kind": "concept", "lang": "en", "question": "How does round-robin scheduling work?", "steps": ["Queue processes.", "Run each one quantum.", "Cycle repeats."], "subject": "computer_science", "text": "Answer: Cycling time quanta.\nSteps:\n1. Queue processes.\n2. Run each one quantum.\n3. Cycle repeats.", "topic": "operating_systems"}
{"answer": "One cycle over 3 processes at 10 ms takes 30 ms.", "choices": null, "id": "cs_0131", "kind": "worked_example", "lang": "en", "question": "Quantum 10 ms, 3 processes. How long is one cycle?", "steps": ["Each runs 10 ms.", "Three in cycle.", "Total = 30 ms."], "subject": "computer_science", "text": "Answer: 30 ms.\nSteps:\n1. Each runs 10 ms.\n2. Three in cycle.\n3. Total = 30 ms.", "topic": "operating_systems"}
{"answer": "Kernel mode runs privileged instructions; user mode cannot.", "choices": {"A": "Slower", "B": "Privileged", "C": "Optional", "D": "Removed"}, "id": "cs_0132", "kind": "multiple_choice", "lang": "en", "question": "How is kernel mode best described?", "steps": ["Full hardware access.", "Privileged level.", "Select option B."], "subject": "computer_science", "text": "Answer: Privileged.\nSteps:\n1. Full hardware access.\n2. Privileged level.\n3. Select option B.\nAnswer: (B)", "topic": "operating_systems"}
{"answer": "Vlákno je lehká jednotka běhu sdílející paměť procesu.", "choices": null, "id": "cs_0133", "kind": "concept", "lang": "cs", "question": "Co je vlákno (thread)?", "steps": ["Běží uvnitř procesu.", "Sdílí paměť.", "Vlastní zásobník."], "subject": "computer_science", "text": "Answer: Lehká jednotka běhu.\nSteps:\n1. Běží uvnitř procesu.\n2. Sdílí paměť.\n3. Vlastní zásobník.", "topic": "operating_systems"}
{"answer": "Inodes store file metadata and block pointers.", "choices": null, "id": "cs_0134", "kind": "concept", "lang": "en", "question": "What is an inode?", "steps": ["Metadata per file.", "Points to blocks.", "Name lives in directory."], "subject": "computer_science", "text": "Answer: File metadata node.\nSteps:\n1. Metadata per file.\n2. Points to blocks.\n3. Name lives in directory.", "topic": "operating_systems"}
{"answer": "A mutex grants one holder at a time, ensuring mutual exclusion.", "choices": {"A": "Mutual exclusion", "B": "Parallel access", "C": "No locking", "D": "Deadlock"}, "id": "cs_0135", "kind": "multiple_choice", "lang": "en", "question": "What does a mutex ensure?", "steps": ["One holder only.", "Others wait.", "Select option A."], "subject": "computer_science", "text": "Answer: Mutual exclusion.\nSteps:\n1. One holder only.\n2. Others wait.\n3. Select option A.\nAnswer: (A)", "topic": "operating_systems"}
{"answer": "A class is a blueprint; objects are its instances.", "choices": null, "id": "cs_0136", "kind": "concept", "lang": "en", "question": "How do classes and objects differ?", "steps": ["Class defines shape.", "Object holds data.", "Many objects per class."], "subject": "computer_science", "text": "Answer: Blueprint versus instance.\nSteps:\n1. Class defines shape.\n2. Object holds data.\n3. Many objects per class.", "topic": "oop"}
{"answer": "The class is the blueprint; objects instantiate it.", "choices": {"A": "Object", "B": "Class", "C": "Method", "D": "Field"}, "id": "cs_0137", "kind": "multiple_choice", "lang": "en", "question": "What is the blueprint?", "steps": ["Blueprint defines.", "That is class.", "Select option B."], "subject": "computer_science", "text": "Answer: Class.\nSteps:\n1. Blueprint defines.\n2. That is class.\n3. Select option B.\nAnswer: (B)", "topic": "oop"}
{"answer": "Two increments raise count from 0 to 2.", "choices": null, "id": "cs_0138", "kind": "worked_example", "lang": "en", "question": "Counter starts at 0, inc() twice. What is count?", "steps": ["Start 0.", "First inc: 1.", "Second inc: 2."], "subject": "computer_science", "text": "Answer: 2.\nSteps:\n1. Start 0.\n2. First inc: 1.\n3. Second inc: 2.", "topic": "oop"}
{"answer": "Třída je předpis, objekt jeho konkrétní instance.", "choices": null, "id": "cs_0139", "kind": "concept", "lang": "cs", "question": "Co je třída a objekt?", "steps": ["Třída definuje tvar.", "Objekt drží data.", "Mnoho objektů z třídy."], "subject": "computer_science", "text": "Answer: Předpis versus instance.\nSteps:\n1. Třída definuje tvar.\n2. Objekt drží data.\n3. Mnoho objektů z třídy.", "topic": "oop"}
{"answer": "Encapsulation bundles data with methods and hides internals.", "choices": null, "id": "cs_0140", "kind": "concept", "lang": "en", "question": "What is encapsulation?", "steps": ["Bundle data, methods.", "Hide internals.", "Expose interface."], "subject": "computer_science", "text": "Answer: Bundled hidden data.\nSteps:\n1. Bundle data, methods.\n2. Hide internals.\n3. Expose interface.", "topic": "oop"}
{"answer": "Encapsulation hides internal details behind an interface.", "choices": {"A": "Encapsulation", "B": "Inheritance", "C": "Polymorphism", "D": "Abstraction"}, "id": "cs_0141", "kind": "multiple_choice", "lang": "en", "question": "What hides internal details?", "steps": ["Need hiding.", "That is encapsulation.", "Select option A."], "subject": "computer_science", "text": "Answer: Encapsulation.\nSteps:\n1. Need hiding.\n2. That is encapsulation.\n3. Select option A.\nAnswer: (A)", "topic": "oop"}
{"answer": "Dog inherits speak and returns 'woof'.", "choices": null, "id": "cs_0142", "kind": "worked_example", "lang": "en", "question": "Dog(Animal) defines speak() as 'woof'. What does Dog().speak() give?", "steps": ["Dog inherits Animal.", "speak returns 'woof'.", "Result 'woof'."], "subject": "computer_science", "text": "Answer: 'woof'.\nSteps:\n1. Dog inherits Animal.\n2. speak returns 'woof'.\n3. Result 'woof'.", "topic": "oop"}
{"answer": "Dědičnost přebírá vlastnosti rodičovské třídy.", "choices": null, "id": "cs_0143", "kind": "concept", "lang": "cs", "question": "Co je dědičnost?", "steps": ["Potomek dědí.", "Rozšiřuje rodiče.", "Opakuje méně kódu."], "subject": "computer_science", "text": "Answer: Přebírání od rodiče.\nSteps:\n1. Potomek dědí.\n2. Rozšiřuje rodiče.\n3. Opakuje méně kódu.", "topic": "oop"}
{"answer": "Polymorphism lets one interface behave differently per type.", "choices": {"A": "Encapsulation", "B": "Inheritance", "C": "Polymorphism", "D": "Coupling"}, "id": "cs_0144", "kind": "multiple_choice", "lang": "en", "question": "What gives one interface many behaviors?", "steps": ["Same call, varied act.", "That is polymorphism.", "Select option C."], "subject": "computer_science", "text": "Answer: Polymorphism.\nSteps:\n1. Same call, varied act.\n2. That is polymorphism.\n3. Select option C.\nAnswer: (C)", "topic": "oop"}
{"answer": "len() calls __len__, returning 3.", "choices": null, "id": "cs_0145", "kind": "worked_example", "lang": "en", "question": "A class defines __len__ returning 3. What is len(obj)?", "steps": ["len calls __len__.", "Method returns 3.", "Result 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. len calls __len__.\n2. Method returns 3.\n3. Result 3.", "topic": "oop"}
{"answer": "__init__ initializes new instances with starting state.", "choices": null, "id": "cs_0146", "kind": "concept", "lang": "en", "question": "What is a constructor in Python?", "steps": ["Called at creation.", "Method __init__.", "Sets attributes."], "subject": "computer_science", "text": "Answer: __init__ initializer.\nSteps:\n1. Called at creation.\n2. Method __init__.\n3. Sets attributes.", "topic": "oop"}
{"answer": "Rectangle(3, 4).area() = 3 x 4 = 12.", "choices": null, "id": "cs_0147", "kind": "worked_example", "lang": "en", "question": "Rectangle(3, 4).area() with area = w*h. What value?", "steps": ["Width 3, height 4.", "Multiply: 12.", "Result 12."], "subject": "computer_science", "text": "Answer: 12.\nSteps:\n1. Width 3, height 4.\n2. Multiply: 12.\n3. Result 12.", "topic": "oop"}
{"answer": "self refers to the current instance inside methods.", "choices": {"A": "Class", "B": "Module", "C": "Parent", "D": "Instance"}, "id": "cs_0148", "kind": "multiple_choice", "lang": "en", "question": "What does self refer to?", "steps": ["Method context.", "Current object.", "Select option D."], "subject": "computer_science", "text": "Answer: Instance.\nSteps:\n1. Method context.\n2. Current object.\n3. Select option D.\nAnswer: (D)", "topic": "oop"}
{"answer": "Polymorfismus umožňuje stejné rozhraní s různým chováním.", "choices": null, "id": "cs_0149", "kind": "concept", "lang": "cs", "question": "Co je polymorfismus?", "steps": ["Stejné volání.", "Různé chování.", "Podle typu objektu."], "subject": "computer_science", "text": "Answer: Jedno rozhraní, více chování.\nSteps:\n1. Stejné volání.\n2. Různé chování.\n3. Podle typu objektu.", "topic": "oop"}
{"answer": "Child overrides greet, so it returns 'hi child'.", "choices": null, "id": "cs_0150", "kind": "worked_example", "lang": "en", "question": "Child overrides greet() with 'hi child'. What does Child().greet() give?", "steps": ["Child defines greet.", "Override wins.", "Result 'hi child'."], "subject": "computer_science", "text": "Answer: 'hi child'.\nSteps:\n1. Child defines greet.\n2. Override wins.\n3. Result 'hi child'.", "topic": "oop"}
{"answer": "Selection sort repeatedly picks the minimum and swaps it forward.", "choices": null, "id": "cs_0151", "kind": "concept", "lang": "en", "question": "How does selection sort work?", "steps": ["Find minimum unsorted.", "Swap to front.", "Repeat for rest."], "subject": "computer_science", "text": "Answer: Pick min, swap forward.\nSteps:\n1. Find minimum unsorted.\n2. Swap to front.\n3. Repeat for rest.", "topic": "algorithms"}
{"answer": "Selection sort always scans quadratically: O(n^2).", "choices": {"A": "O(n^2)", "B": "O(n log n)", "C": "O(n)", "D": "O(log n)"}, "id": "cs_0152", "kind": "multiple_choice", "lang": "en", "question": "What is selection sort's complexity?", "steps": ["n passes over n.", "Quadratic total.", "Select option A."], "subject": "computer_science", "text": "Answer: O(n^2).\nSteps:\n1. n passes over n.\n2. Quadratic total.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "Selection sort gives [10,14,29] after two swaps.", "choices": null, "id": "cs_0153", "kind": "worked_example", "lang": "en", "question": "Selection-sort [29,10,14]. What are the steps?", "steps": ["Min is 10: swap to [10,29,14].", "Min of rest is 14: swap to [10,14,29].", "Sorted in 2 swaps."], "subject": "computer_science", "text": "Answer: [10,14,29].\nSteps:\n1. Min is 10: swap to [10,29,14].\n2. Min of rest is 14: swap to [10,14,29].\n3. Sorted in 2 swaps.", "topic": "algorithms"}
{"answer": "Třídění výběrem hledá minimum a přesouvá ho dopředu.", "choices": null, "id": "cs_0154", "kind": "concept", "lang": "cs", "question": "Co je třídění výběrem?", "steps": ["Najdi minimum.", "Prohoď dopředu.", "Opakuj pro zbytek."], "subject": "computer_science", "text": "Answer: Výběr minima dopředu.\nSteps:\n1. Najdi minimum.\n2. Prohoď dopředu.\n3. Opakuj pro zbytek.", "topic": "algorithms"}
{"answer": "Linear search worst case scans everything: O(n).", "choices": {"A": "O(1)", "B": "O(n)", "C": "O(log n)", "D": "O(n^2)"}, "id": "cs_0155", "kind": "multiple_choice", "lang": "en", "question": "What is linear search's worst case?", "steps": ["Target last or absent.", "Scan all n.", "Select option B."], "subject": "computer_science", "text": "Answer: O(n).\nSteps:\n1. Target last or absent.\n2. Scan all n.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "Searching 9 in [1..8] takes 8 comparisons and fails.", "choices": null, "id": "cs_0156", "kind": "worked_example", "lang": "en", "question": "Linear search for 9 in [1,2,3,4,5,6,7,8]. How many comparisons?", "steps": ["Check each of 8.", "None matches.", "8 comparisons, not found."], "subject": "computer_science", "text": "Answer: 8, not found.\nSteps:\n1. Check each of 8.\n2. None matches.\n3. 8 comparisons, not found.", "topic": "algorithms"}
{"answer": "Greedy algorithms take the locally best step hoping for global optimum.", "choices": null, "id": "cs_0157", "kind": "concept", "lang": "en", "question": "What is a greedy algorithm?", "steps": ["Choose best now.", "Never backtrack.", "Example: coin change."], "subject": "computer_science", "text": "Answer: Locally best steps.\nSteps:\n1. Choose best now.\n2. Never backtrack.\n3. Example: coin change.", "topic": "algorithms"}
{"answer": "Faktoriál 4 je 24, tedy 4 x 3 x 2 x 1.", "choices": null, "id": "cs_0158", "kind": "worked_example", "lang": "cs", "question": "Vypočítej faktoriál(4).", "steps": ["4 x faktoriál(3).", "Rozviň: 4x3x2x1.", "Výsledek = 24."], "subject": "computer_science", "text": "Answer: 24.\nSteps:\n1. 4 x faktoriál(3).\n2. Rozviň: 4x3x2x1.\n3. Výsledek = 24.", "topic": "algorithms"}
{"answer": "BFS uses a queue to expand level by level.", "choices": {"A": "Stack", "B": "Heap", "C": "Queue", "D": "Tree"}, "id": "cs_0159", "kind": "multiple_choice", "lang": "en", "question": "Which structure does BFS use?", "steps": ["Level order needed.", "Queue gives FIFO.", "Select option C."], "subject": "computer_science", "text": "Answer: Queue.\nSteps:\n1. Level order needed.\n2. Queue gives FIFO.\n3. Select option C.\nAnswer: (C)", "topic": "algorithms"}
{"answer": "Divide and conquer splits problems, solves parts, and combines answers.", "choices": null, "id": "cs_0160", "kind": "concept", "lang": "en", "question": "What is divide and conquer?", "steps": ["Divide input.", "Conquer parts.", "Combine results."], "subject": "computer_science", "text": "Answer: Split, solve, combine.\nSteps:\n1. Divide input.\n2. Conquer parts.\n3. Combine results.", "topic": "algorithms"}
{"answer": "Merging [1,4] and [2,3] gives [1,2,3,4] in 3 comparisons.", "choices": null, "id": "cs_0161", "kind": "worked_example", "lang": "en", "question": "Merge [1,4] and [2,3]. What are the steps?", "steps": ["1 vs 2: take 1.", "4 vs 2: take 2; 4 vs 3: take 3.", "Take 4: [1,2,3,4]."], "subject": "computer_science", "text": "Answer: [1,2,3,4].\nSteps:\n1. 1 vs 2: take 1.\n2. 4 vs 2: take 2; 4 vs 3: take 3.\n3. Take 4: [1,2,3,4].", "topic": "algorithms"}
{"answer": "Dijkstra computes shortest paths in weighted graphs.", "choices": {"A": "MST", "B": "Max flow", "C": "Sorting", "D": "Shortest path"}, "id": "cs_0162", "kind": "multiple_choice", "lang": "en", "question": "What does Dijkstra's algorithm find?", "steps": ["Weighted edges.", "Shortest distances.", "Select option D."], "subject": "computer_science", "text": "Answer: Shortest path.\nSteps:\n1. Weighted edges.\n2. Shortest distances.\n3. Select option D.\nAnswer: (D)", "topic": "algorithms"}
{"answer": "Hladový algoritmus volí lokálně nejlepší krok.", "choices": null, "id": "cs_0163", "kind": "concept", "lang": "cs", "question": "Co je hladový algoritmus?", "steps": ["Nejlepší krok teď.", "Bez návratu.", "Příklad: mince."], "subject": "computer_science", "text": "Answer: Lokálně nejlepší kroky.\nSteps:\n1. Nejlepší krok teď.\n2. Bez návratu.\n3. Příklad: mince.", "topic": "algorithms"}
{"answer": "Merge sort averages O(n log n).", "choices": {"A": "Bubble sort", "B": "Merge sort", "C": "Selection sort", "D": "Insertion sort"}, "id": "cs_0164", "kind": "multiple_choice", "lang": "en", "question": "Which averages O(n log n)?", "steps": ["Others are quadratic.", "Merge divides evenly.", "Select option B."], "subject": "computer_science", "text": "Answer: Merge sort.\nSteps:\n1. Others are quadratic.\n2. Merge divides evenly.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "3-disk Hanoi needs 7 moves (2^3 - 1).", "choices": null, "id": "cs_0165", "kind": "worked_example", "lang": "en", "question": "How many moves for 3-disk Tower of Hanoi?", "steps": ["Formula: 2^n - 1.", "Substitute: 8 - 1.", "Moves = 7."], "subject": "computer_science", "text": "Answer: 7.\nSteps:\n1. Formula: 2^n - 1.\n2. Substitute: 8 - 1.\n3. Moves = 7.", "topic": "algorithms"}
{"answer": "Big-Omega gives a lower growth bound.", "choices": null, "id": "cs_0166", "kind": "concept", "lang": "en", "question": "What is Big-Omega notation?", "steps": ["At least this fast.", "Lower bound.", "Example: Omega(n)."], "subject": "computer_science", "text": "Answer: Lower bound.\nSteps:\n1. At least this fast.\n2. Lower bound.\n3. Example: Omega(n).", "topic": "complexity"}
{"answer": "Omega bounds growth from below.", "choices": {"A": "Lower bound", "B": "Upper bound", "C": "Exact bound", "D": "No bound"}, "id": "cs_0167", "kind": "multiple_choice", "lang": "en", "question": "What does Omega describe?", "steps": ["Minimum growth.", "Lower bound.", "Select option A."], "subject": "computer_science", "text": "Answer: Lower bound.\nSteps:\n1. Minimum growth.\n2. Lower bound.\n3. Select option A.\nAnswer: (A)", "topic": "complexity"}
{"answer": "A triple loop with n = 10 runs 1,000 iterations.", "choices": null, "id": "cs_0168", "kind": "worked_example", "lang": "en", "question": "How many iterations for triple nested loops with n = 10?", "steps": ["Each level runs 10.", "Total = 10^3.", "Iterations = 1,000."], "subject": "computer_science", "text": "Answer: 1,000.\nSteps:\n1. Each level runs 10.\n2. Total = 10^3.\n3. Iterations = 1,000.", "topic": "complexity"}
{"answer": "Nejlepší případ je nejrychlejší možný vstup.", "choices": null, "id": "cs_0169", "kind": "concept", "lang": "cs", "question": "Co je nejlepší případ?", "steps": ["Nejrychlejší vstup.", "Dolní odhad.", "Příklad: prvek první."], "subject": "computer_science", "text": "Answer: Nejrychlejší vstup.\nSteps:\n1. Nejrychlejší vstup.\n2. Dolní odhad.\n3. Příklad: prvek první.", "topic": "complexity"}
{"answer": "O(n log n) grows slower than O(n^2).", "choices": {"A": "O(n)", "B": "O(log n)", "C": "O(n^2)", "D": "O(1)"}, "id": "cs_0170", "kind": "multiple_choice", "lang": "en", "question": "Which is slower than O(n log n)?", "steps": ["Compare growth.", "Quadratic exceeds.", "Select option C."], "subject": "computer_science", "text": "Answer: O(n^2).\nSteps:\n1. Compare growth.\n2. Quadratic exceeds.\n3. Select option C.\nAnswer: (C)", "topic": "complexity"}
{"answer": "Big-Theta bounds growth tightly from both sides.", "choices": null, "id": "cs_0171", "kind": "concept", "lang": "en", "question": "What is Big-Theta notation?", "steps": ["Upper and lower.", "Tight bound.", "Example: Theta(n log n)."], "subject": "computer_science", "text": "Answer: Tight bound.\nSteps:\n1. Upper and lower.\n2. Tight bound.\n3. Example: Theta(n log n).", "topic": "complexity"}
{"answer": "log2(1,000,000) is about 20, since 2^20 = 1,048,576.", "choices": null, "id": "cs_0172", "kind": "worked_example", "lang": "en", "question": "About how many binary search steps for n = 1,000,000?", "steps": ["Steps = log2(n).", "2^20 ≈ 1,000,000.", "About 20 steps."], "subject": "computer_science", "text": "Answer: 20.\nSteps:\n1. Steps = log2(n).\n2. 2^20 ≈ 1,000,000.\n3. About 20 steps.", "topic": "complexity"}
{"answer": "Smyčka O(n) s n = 1000 udělá 1000 kroků.", "choices": null, "id": "cs_0173", "kind": "worked_example", "lang": "cs", "question": "Kolik kroků má smyčka O(n) pro n = 1000?", "steps": ["Jeden průchod na prvek.", "n = 1000.", "Celkem 1000 kroků."], "subject": "computer_science", "text": "Answer: 1000.\nSteps:\n1. Jeden průchod na prvek.\n2. n = 1000.\n3. Celkem 1000 kroků.", "topic": "complexity"}
{"answer": "Big-O drops constant factors and keeps growth shape.", "choices": {"A": "Counted exactly", "B": "Ignored", "C": "Doubled", "D": "Logged"}, "id": "cs_0174", "kind": "multiple_choice", "lang": "en", "question": "What happens to constants in Big-O?", "steps": ["Only growth matters.", "Constants dropped.", "Select option B."], "subject": "computer_science", "text": "Answer: Ignored.\nSteps:\n1. Only growth matters.\n2. Constants dropped.\n3. Select option B.\nAnswer: (B)", "topic": "complexity"}
{"answer": "O(2^n) doubles work per added input, exploding fast.", "choices": null, "id": "cs_0175", "kind": "concept", "lang": "en", "question": "What is exponential complexity?", "steps": ["Doubles per input.", "Example: subsets.", "Infeasible past n ~ 30."], "subject": "computer_science", "text": "Answer: Doubling per input.\nSteps:\n1. Doubles per input.\n2. Example: subsets.\n3. Infeasible past n ~ 30.", "topic": "complexity"}
{"answer": "10 items have 2^10 = 1024 subsets.", "choices": null, "id": "cs_0176", "kind": "worked_example", "lang": "en", "question": "How many subsets does a 10-item set have?", "steps": ["Each item in or out.", "Total = 2^10.", "Subsets = 1024."], "subject": "computer_science", "text": "Answer: 1024.\nSteps:\n1. Each item in or out.\n2. Total = 2^10.\n3. Subsets = 1024.", "topic": "complexity"}
{"answer": "O(2^n) outgrows all polynomial bounds.", "choices": {"A": "O(n^2)", "B": "O(n^3)", "C": "O(n log n)", "D": "O(2^n)"}, "id": "cs_0177", "kind": "multiple_choice", "lang": "en", "question": "Which grows fastest?", "steps": ["Exponential beats polynomial.", "2^n wins.", "Select option D."], "subject": "computer_science", "text": "Answer: O(2^n).\nSteps:\n1. Exponential beats polynomial.\n2. 2^n wins.\n3. Select option D.\nAnswer: (D)", "topic": "complexity"}
{"answer": "Exponenciální složitost zdvojnásobuje práci s každým vstupem.", "choices": null, "id": "cs_0178", "kind": "concept", "lang": "cs", "question": "Co je exponenciální složitost?", "steps": ["Dvojnásobek na vstup.", "Příklad: podmnožiny.", "Nezvládnutelná pro velká n."], "subject": "computer_science", "text": "Answer: Dvojnásobení na vstup.\nSteps:\n1. Dvojnásobek na vstup.\n2. Příklad: podmnožiny.\n3. Nezvládnutelná pro velká n.", "topic": "complexity"}
{"answer": "O(n) needs 1e6 steps while O(n^2) needs 1e12 for n = 1e6.", "choices": null, "id": "cs_0179", "kind": "worked_example", "lang": "en", "question": "Compare O(n) vs O(n^2) steps for n = 1,000,000.", "steps": ["O(n): 1,000,000.", "O(n^2): 10^12.", "Quadratic is a trillion."], "subject": "computer_science", "text": "Answer: 1e6 vs 1e12.\nSteps:\n1. O(n): 1,000,000.\n2. O(n^2): 10^12.\n3. Quadratic is a trillion.", "topic": "complexity"}
{"answer": "NP-complete problems are the hardest in NP.", "choices": {"A": "Hardest in NP", "B": "Easy", "C": "Unsolvable", "D": "Linear"}, "id": "cs_0180", "kind": "multiple_choice", "lang": "en", "question": "What does NP-complete mean?", "steps": ["In NP class.", "All NP reduces to it.", "Select option A."], "subject": "computer_science", "text": "Answer: Hardest in NP.\nSteps:\n1. In NP class.\n2. All NP reduces to it.\n3. Select option A.\nAnswer: (A)", "topic": "complexity"}
{"answer": "Doubly linked lists add backward pointers for two-way traversal.", "choices": null, "id": "cs_0181", "kind": "concept", "lang": "en", "question": "What is a doubly linked list?", "steps": ["Each node two links.", "Forward and back.", "Costs extra memory."], "subject": "computer_science", "text": "Answer: Two-way linked nodes.\nSteps:\n1. Each node two links.\n2. Forward and back.\n3. Costs extra memory.", "topic": "data_structures"}
{"answer": "Backward links allow traversal both ways.", "choices": {"A": "Forward only", "B": "Both directions", "C": "Random only", "D": "No traversal"}, "id": "cs_0182", "kind": "multiple_choice", "lang": "en", "question": "How can doubly lists traverse?", "steps": ["Two pointers exist.", "Both ways work.", "Select option B."], "subject": "computer_science", "text": "Answer: Both directions.\nSteps:\n1. Two pointers exist.\n2. Both ways work.\n3. Select option B.\nAnswer: (B)", "topic": "data_structures"}
{"answer": "Popping after pushing 1, 2 gives 2 then 1.", "choices": null, "id": "cs_0183", "kind": "worked_example", "lang": "en", "question": "Push 1, 2 onto a stack, pop twice. What order?", "steps": ["Top is 2: pop 2.", "Top is 1: pop 1.", "Order 2, 1."], "subject": "computer_science", "text": "Answer: 2, 1.\nSteps:\n1. Top is 2: pop 2.\n2. Top is 1: pop 1.\n3. Order 2, 1.", "topic": "data_structures"}
{"answer": "Spojový seznam spojuje uzly ukazateli.", "choices": null, "id": "cs_0184", "kind": "concept", "lang": "cs", "question": "Co je spojový seznam?", "steps": ["Uzly s daty.", "Ukazatele na další.", "Rychlé vkládání."], "subject": "computer_science", "text": "Answer: Uzly s ukazateli.\nSteps:\n1. Uzly s daty.\n2. Ukazatele na další.\n3. Rychlé vkládání.", "topic": "data_structures"}
{"answer": "Hash tables average O(1) lookup via direct indexing.", "choices": {"A": "O(1)", "B": "O(n)", "C": "O(log n)", "D": "O(n^2)"}, "id": "cs_0185", "kind": "multiple_choice", "lang": "en", "question": "What is average hash lookup time?", "steps": ["Hash to slot.", "Direct access.", "Select option A."], "subject": "computer_science", "text": "Answer: O(1).\nSteps:\n1. Hash to slot.\n2. Direct access.\n3. Select option A.\nAnswer: (A)", "topic": "data_structures"}
{"answer": "Load factor is 6/8 = 0.75.", "choices": null, "id": "cs_0186", "kind": "worked_example", "lang": "en", "question": "6 items in 8 slots. What is the load factor?", "steps": ["Divide items by slots.", "6/8 = 0.75.", "Load = 0.75."], "subject": "computer_science", "text": "Answer: 0.75.\nSteps:\n1. Divide items by slots.\n2. 6/8 = 0.75.\n3. Load = 0.75.", "topic": "data_structures"}
{"answer": "A BST orders keys left-smaller, right-larger; plain trees do not.", "choices": null, "id": "cs_0187", "kind": "concept", "lang": "en", "question": "How do binary trees and BSTs differ?", "steps": ["Binary: two children.", "BST adds ordering.", "Ordering enables search."], "subject": "computer_science", "text": "Answer: Ordering rule added.\nSteps:\n1. Binary: two children.\n2. BST adds ordering.\n3. Ordering enables search.", "topic": "data_structures"}
{"answer": "Vyvážený strom se 7 uzly má hloubku 3.", "choices": null, "id": "cs_0188", "kind": "worked_example", "lang": "cs", "question": "Jaká je hloubka vyváženého stromu se 7 uzly?", "steps": ["Úrovně: 1, 2, 4.", "Celkem 7 uzlů.", "Hloubka = 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Úrovně: 1, 2, 4.\n2. Celkem 7 uzlů.\n3. Hloubka = 3.", "topic": "data_structures"}
{"answer": "Children of node i sit at 2i+1 and 2i+2 in array heaps.", "choices": {"A": "i+1, i+2", "B": "2i, 2i+1", "C": "2i+1, 2i+2", "D": "i/2"}, "id": "cs_0189", "kind": "multiple_choice", "lang": "en", "question": "Where are children in an array heap?", "steps": ["Zero-based array.", "Left 2i+1, right 2i+2.", "Select option C."], "subject": "computer_science", "text": "Answer: 2i+1, 2i+2.\nSteps:\n1. Zero-based array.\n2. Left 2i+1, right 2i+2.\n3. Select option C.\nAnswer: (C)", "topic": "data_structures"}
{"answer": "Adjacency lists store neighbors per node; matrices store a full V x V grid.", "choices": null, "id": "cs_0190", "kind": "concept", "lang": "en", "question": "How do adjacency lists and matrices differ?", "steps": ["Lists: per-node neighbors.", "Matrix: full grid.", "Lists save sparse space."], "subject": "computer_science", "text": "Answer: Neighbors versus grid.\nSteps:\n1. Lists: per-node neighbors.\n2. Matrix: full grid.\n3. Lists save sparse space.", "topic": "data_structures"}
{"answer": "K5 has 5 x 4 / 2 = 10 edges.", "choices": null, "id": "cs_0191", "kind": "worked_example", "lang": "en", "question": "How many edges in complete graph K5?", "steps": ["Formula: n(n-1)/2.", "Substitute: 5x4/2.", "Edges = 10."], "subject": "computer_science", "text": "Answer: 10.\nSteps:\n1. Formula: n(n-1)/2.\n2. Substitute: 5x4/2.\n3. Edges = 10.", "topic": "data_structures"}
{"answer": "A V x V matrix uses O(V^2) space.", "choices": {"A": "O(V)", "B": "O(E)", "C": "O(V+E)", "D": "O(V^2)"}, "id": "cs_0192", "kind": "multiple_choice", "lang": "en", "question": "What space does an adjacency matrix use?", "steps": ["V rows, V cols.", "V squared cells.", "Select option D."], "subject": "computer_science", "text": "Answer: O(V^2).\nSteps:\n1. V rows, V cols.\n2. V squared cells.\n3. Select option D.\nAnswer: (D)", "topic": "data_structures"}
{"answer": "Halda je strom, kde rodič je menší (či větší) než děti.", "choices": null, "id": "cs_0193", "kind": "concept", "lang": "cs", "question": "Co je halda (heap)?", "steps": ["Stromová struktura.", "Rodič extrémní.", "Kořen minimum či maximum."], "subject": "computer_science", "text": "Answer: Strom s extrémem.\nSteps:\n1. Stromová struktura.\n2. Rodič extrémní.\n3. Kořen minimum či maximum.", "topic": "data_structures"}
{"answer": "Heaps give O(log n) priority queue operations.", "choices": {"A": "Stack", "B": "Heap", "C": "Queue", "D": "Array"}, "id": "cs_0194", "kind": "multiple_choice", "lang": "en", "question": "What implements a priority queue?", "steps": ["Need min/max fast.", "Heap provides it.", "Select option B."], "subject": "computer_science", "text": "Answer: Heap.\nSteps:\n1. Need min/max fast.\n2. Heap provides it.\n3. Select option B.\nAnswer: (B)", "topic": "data_structures"}
{"answer": "Inserting 5, 3, 4 into a min-heap leaves root 3.", "choices": null, "id": "cs_0195", "kind": "worked_example", "lang": "en", "question": "Insert 5, 3, 4 into a min-heap. What is the root?", "steps": ["Insert 5: root 5.", "Insert 3: bubbles to root.", "Insert 4: root stays 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Insert 5: root 5.\n2. Insert 3: bubbles to root.\n3. Insert 4: root stays 3.", "topic": "data_structures"}
{"answer": "String methods like upper() and split() transform text.", "choices": null, "id": "cs_0196", "kind": "concept", "lang": "en", "question": "What do Python string methods do?", "steps": ["upper() capitalizes.", "split() divides.", "strip() trims."], "subject": "computer_science", "text": "Answer: Transform text.\nSteps:\n1. upper() capitalizes.\n2. split() divides.\n3. strip() trims.", "topic": "python"}
{"answer": "'a,b'.split(',') gives ['a', 'b'].", "choices": {"A": "['a','b']", "B": "'ab'", "C": "['a,b']", "D": "Error"}, "id": "cs_0197", "kind": "multiple_choice", "lang": "en", "question": "What does 'a,b'.split(',') return?", "steps": ["Split on comma.", "Two parts.", "Select option A."], "subject": "computer_science", "text": "Answer: ['a','b'].\nSteps:\n1. Split on comma.\n2. Two parts.\n3. Select option A.\nAnswer: (A)", "topic": "python"}
{"answer": "'hello'.upper() returns 'HELLO'.", "choices": null, "id": "cs_0198", "kind": "worked_example", "lang": "en", "question": "What does 'hello'.upper() return?", "steps": ["Capitalize each letter.", "Result HELLO.", "Returns 'HELLO'."], "subject": "computer_science", "text": "Answer: 'HELLO'.\nSteps:\n1. Capitalize each letter.\n2. Result HELLO.\n3. Returns 'HELLO'.", "topic": "python"}
{"answer": "Řetězec je neměnná posloupnost znaků.", "choices": null, "id": "cs_0199", "kind": "concept", "lang": "cs", "question": "Co je řetězec (str)?", "steps": ["Posloupnost znaků.", "Neměnný typ.", "Metody upper, split."], "subject": "computer_science", "text": "Answer: Neměnné znaky.\nSteps:\n1. Posloupnost znaků.\n2. Neměnný typ.\n3. Metody upper, split.", "topic": "python"}
{"answer": "list.append mutates in place and returns None.", "choices": {"A": "New list", "B": "Length", "C": "None", "D": "True"}, "id": "cs_0200", "kind": "multiple_choice", "lang": "en", "question": "What does append() return?", "steps": ["Mutates in place.", "No value built.", "Select option C."], "subject": "computer_science", "text": "Answer: None.\nSteps:\n1. Mutates in place.\n2. No value built.\n3. Select option C.\nAnswer: (C)", "topic": "python"}
{"answer": "append() adds one item while extend() adds each item from an iterable.", "choices": null, "id": "cs_0201", "kind": "concept", "lang": "en", "question": "How do append() and extend() differ?", "steps": ["append takes one object.", "extend iterates input.", "Use extend to merge lists."], "subject": "computer_science", "text": "Answer: One item versus many.\nSteps:\n1. append takes one object.\n2. extend iterates input.\n3. Use extend to merge lists.", "topic": "python"}
{"answer": "[1,2,3].length is 3.", "choices": {"A": "2", "B": "3", "C": "4", "D": "undefined"}, "id": "cs_0202", "kind": "multiple_choice", "lang": "en", "question": "What does [1,2,3].length return?", "steps": ["Count elements.", "Three items.", "Select option B."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Count elements.\n2. Three items.\n3. Select option B.\nAnswer: (B)", "topic": "javascript"}
{"answer": "SELECT 7 * 6 returns 42.", "choices": null, "id": "cs_0203", "kind": "worked_example", "lang": "en", "question": "What does SELECT 7 * 6 return?", "steps": ["Multiply 7 by 6.", "7 x 6 = 42.", "Result is 42."], "subject": "computer_science", "text": "Answer: 42.\nSteps:\n1. Multiply 7 by 6.\n2. 7 x 6 = 42.\n3. Result is 42.", "topic": "sql"}
{"answer": "A /26 network has 62 usable hosts.", "choices": null, "id": "cs_0204", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in a /26 network?", "steps": ["Host bits = 32 - 26 = 6.", "Addresses = 2^6 = 64.", "Usable = 64 - 2 = 62."], "subject": "computer_science", "text": "Answer: 62.\nSteps:\n1. Host bits = 32 - 26 = 6.\n2. Addresses = 2^6 = 64.\n3. Usable = 64 - 2 = 62.", "topic": "networking"}
{"answer": "C v ACID znamená konzistence.", "choices": {"A": "Atomicita", "B": "Konzistence", "C": "Izolace", "D": "Trvanlivost"}, "id": "cs_0205", "kind": "multiple_choice", "lang": "cs", "question": "Co znamená C v ACID?", "steps": ["ACID vlastnosti.", "C je konzistence.", "Vyber možnost B."], "subject": "computer_science", "text": "Answer: Konzistence.\nSteps:\n1. ACID vlastnosti.\n2. C je konzistence.\n3. Vyber možnost B.\nAnswer: (B)", "topic": "databases"}
{"answer": "A context switch saves one process state and restores another.", "choices": null, "id": "cs_0206", "kind": "concept", "lang": "en", "question": "What is a context switch?", "steps": ["Save registers and state.", "Load next process.", "Resume execution."], "subject": "computer_science", "text": "Answer: Swap running process.\nSteps:\n1. Save registers and state.\n2. Load next process.\n3. Resume execution.", "topic": "operating_systems"}
{"answer": "Balance starts at 100, deposit 50 gives 150.", "choices": null, "id": "cs_0207", "kind": "worked_example", "lang": "en", "question": "Account balance 100, deposit(50). What is the balance?", "steps": ["Start at 100.", "Add 50.", "Balance = 150."], "subject": "computer_science", "text": "Answer: 150.\nSteps:\n1. Start at 100.\n2. Add 50.\n3. Balance = 150.", "topic": "oop"}
{"answer": "BFS finds shortest paths in unweighted graphs.", "choices": {"A": "Dijkstra", "B": "BFS", "C": "DFS", "D": "Merge sort"}, "id": "cs_0208", "kind": "multiple_choice", "lang": "en", "question": "Which finds shortest path in unweighted graphs?", "steps": ["Unweighted edges.", "BFS level order.", "Select option B."], "subject": "computer_science", "text": "Answer: BFS.\nSteps:\n1. Unweighted edges.\n2. BFS level order.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "Worst-case analysis bounds runtime over all inputs of size n.", "choices": null, "id": "cs_0209", "kind": "concept", "lang": "en", "question": "What is worst-case analysis?", "steps": ["Consider all inputs.", "Take maximum cost.", "Guarantees an upper bound."], "subject": "computer_science", "text": "Answer: Maximum over inputs.\nSteps:\n1. Consider all inputs.\n2. Take maximum cost.\n3. Guarantees an upper bound.", "topic": "complexity"}
{"answer": "Pop vrátí 6, protože zásobník je LIFO.", "choices": null, "id": "cs_0210", "kind": "worked_example", "lang": "cs", "question": "Zásobník obsahuje 5, 6. Co vrátí pop()?", "steps": ["Nahoře je 6.", "Pop odebere 6.", "Výsledek je 6."], "subject": "computer_science", "text": "Answer: 6.\nSteps:\n1. Nahoře je 6.\n2. Pop odebere 6.\n3. Výsledek je 6.", "topic": "data_structures"}
{"answer": "Tuples are immutable ordered sequences for fixed records.", "choices": null, "id": "cs_0211", "kind": "concept", "lang": "en", "question": "What are Python tuples for?", "steps": ["Ordered items.", "Cannot change.", "Good for records."], "subject": "computer_science", "text": "Answer: Immutable records.\nSteps:\n1. Ordered items.\n2. Cannot change.\n3. Good for records.", "topic": "python"}
{"answer": "typeof 'hi' is 'string'.", "choices": {"A": "string", "B": "number", "C": "object", "D": "undefined"}, "id": "cs_0212", "kind": "multiple_choice", "lang": "en", "question": "What is typeof 'hi'?", "steps": ["'hi' is text.", "Type is string.", "Select option A."], "subject": "computer_science", "text": "Answer: string.\nSteps:\n1. 'hi' is text.\n2. Type is string.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "COUNT returns 4 when 4 of 10 rows match.", "choices": null, "id": "cs_0213", "kind": "worked_example", "lang": "en", "question": "Table has 10 rows, WHERE matches 4. What does COUNT(*) return?", "steps": ["Filter to 4 rows.", "Count them.", "Result = 4."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Filter to 4 rows.\n2. Count them.\n3. Result = 4.", "topic": "sql"}
{"answer": "10.0.0.0/8 has 2^24 = 16777216 addresses.", "choices": null, "id": "cs_0214", "kind": "worked_example", "lang": "en", "question": "How many addresses in 10.0.0.0/8?", "steps": ["Host bits = 24.", "Total = 2^24.", "Addresses = 16777216."], "subject": "computer_science", "text": "Answer: 16777216.\nSteps:\n1. Host bits = 24.\n2. Total = 2^24.\n3. Addresses = 16777216.", "topic": "networking"}
{"answer": "Řádky přidává příkaz INSERT.", "choices": {"A": "SELECT", "B": "INSERT", "C": "DELETE", "D": "UPDATE"}, "id": "cs_0215", "kind": "multiple_choice", "lang": "cs", "question": "Která operace přidává řádky?", "steps": ["SELECT čte.", "INSERT přidává.", "Vyber možnost B."], "subject": "computer_science", "text": "Answer: INSERT.\nSteps:\n1. SELECT čte.\n2. INSERT přidává.\n3. Vyber možnost B.\nAnswer: (B)", "topic": "databases"}
{"answer": "A system call is the interface for user programs to request kernel services.", "choices": null, "id": "cs_0216", "kind": "concept", "lang": "en", "question": "What is a system call?", "steps": ["User needs kernel help.", "Trap to kernel.", "Return result."], "subject": "computer_science", "text": "Answer: Kernel service request.\nSteps:\n1. User needs kernel help.\n2. Trap to kernel.\n3. Return result.", "topic": "operating_systems"}
{"answer": "Square(5).area() returns 25.", "choices": null, "id": "cs_0217", "kind": "worked_example", "lang": "en", "question": "Square side 5, area = s*s. What does Square(5).area() give?", "steps": ["Side = 5.", "Area = 5 x 5.", "Result = 25."], "subject": "computer_science", "text": "Answer: 25.\nSteps:\n1. Side = 5.\n2. Area = 5 x 5.\n3. Result = 25.", "topic": "oop"}
{"answer": "With early exit, sorted input needs one pass: O(n).", "choices": {"A": "O(n)", "B": "O(n^2)", "C": "O(log n)", "D": "O(1)"}, "id": "cs_0218", "kind": "multiple_choice", "lang": "en", "question": "What is bubble sort best case with early exit?", "steps": ["Sorted input detected.", "One pass.", "Select option A."], "subject": "computer_science", "text": "Answer: O(n).\nSteps:\n1. Sorted input detected.\n2. One pass.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "Amortized analysis averages cost over a sequence of operations.", "choices": null, "id": "cs_0219", "kind": "concept", "lang": "en", "question": "What is amortized analysis?", "steps": ["Many operations.", "Average the cost.", "Example: dynamic array."], "subject": "computer_science", "text": "Answer: Average over sequence.\nSteps:\n1. Many operations.\n2. Average the cost.\n3. Example: dynamic array.", "topic": "complexity"}
{"answer": "Dequeue vrátí 1, protože fronta je FIFO.", "choices": null, "id": "cs_0220", "kind": "worked_example", "lang": "cs", "question": "Fronta obsahuje 1, 2. Co vrátí dequeue?", "steps": ["Vpředu je 1.", "Dequeue odebere 1.", "Výsledek je 1."], "subject": "computer_science", "text": "Answer: 1.\nSteps:\n1. Vpředu je 1.\n2. Dequeue odebere 1.\n3. Výsledek je 1.", "topic": "data_structures"}
{"answer": "Dict comprehensions build dicts as {k: v for ...} in one line.", "choices": null, "id": "cs_0221", "kind": "concept", "lang": "en", "question": "What is a dict comprehension?", "steps": ["Loop inside braces.", "Build key-value pairs.", "Example: {x: x*x}."], "subject": "computer_science", "text": "Answer: One-line dict builder.\nSteps:\n1. Loop inside braces.\n2. Build key-value pairs.\n3. Example: {x: x*x}.", "topic": "python"}
{"answer": "'5' - 2 is 3 because minus coerces to number.", "choices": {"A": "'52'", "B": "3", "C": "'3'", "D": "NaN"}, "id": "cs_0222", "kind": "multiple_choice", "lang": "en", "question": "What does '5' - 2 give in JavaScript?", "steps": ["Minus coerces.", "'5' becomes 5.", "Select option B."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Minus coerces.\n2. '5' becomes 5.\n3. Select option B.\nAnswer: (B)", "topic": "javascript"}
{"answer": "SUM of (10, 20) is 30.", "choices": null, "id": "cs_0223", "kind": "worked_example", "lang": "en", "question": "What does SELECT SUM(x) give for x in (10,20)?", "steps": ["Add values.", "10 + 20 = 30.", "Result = 30."], "subject": "computer_science", "text": "Answer: 30.\nSteps:\n1. Add values.\n2. 10 + 20 = 30.\n3. Result = 30.", "topic": "sql"}
{"answer": "A /30 has 2 usable hosts.", "choices": null, "id": "cs_0224", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in a /30 network?", "steps": ["Host bits = 2.", "Addresses = 4.", "Usable = 4 - 2 = 2."], "subject": "computer_science", "text": "Answer: 2.\nSteps:\n1. Host bits = 2.\n2. Addresses = 4.\n3. Usable = 4 - 2 = 2.", "topic": "networking"}
{"answer": "DELETE maže řádky z tabulky.", "choices": {"A": "Maže řádky", "B": "Přidává řádky", "C": "Třídí řádky", "D": "Spojuje tabulky"}, "id": "cs_0225", "kind": "multiple_choice", "lang": "cs", "question": "Co dělá příkaz DELETE?", "steps": ["DELETE odstraňuje.", "Maže vybrané řádky.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Maže řádky.\nSteps:\n1. DELETE odstraňuje.\n2. Maže vybrané řádky.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "Virtual memory extends RAM using disk space with address translation.", "choices": null, "id": "cs_0226", "kind": "concept", "lang": "en", "question": "What is virtual memory?", "steps": ["Programs see large space.", "OS maps to RAM or disk.", "Enables bigger programs."], "subject": "computer_science", "text": "Answer: RAM extended by disk.\nSteps:\n1. Programs see large space.\n2. OS maps to RAM or disk.\n3. Enables bigger programs.", "topic": "operating_systems"}
{"answer": "Person('Ann', 30).age is 30.", "choices": null, "id": "cs_0227", "kind": "worked_example", "lang": "en", "question": "Person stores name and age. What is Person('Ann', 30).age?", "steps": ["Name is Ann.", "Age is 30.", "Attribute age = 30."], "subject": "computer_science", "text": "Answer: 30.\nSteps:\n1. Name is Ann.\n2. Age is 30.\n3. Attribute age = 30.", "topic": "oop"}
{"answer": "Merge sort guarantees O(n log n) worst case.", "choices": {"A": "Quicksort", "B": "Merge sort", "C": "Bubble sort", "D": "Insertion sort"}, "id": "cs_0228", "kind": "multiple_choice", "lang": "en", "question": "Which sort has O(n log n) worst case?", "steps": ["Quicksort degrades.", "Merge divides evenly.", "Select option B."], "subject": "computer_science", "text": "Answer: Merge sort.\nSteps:\n1. Quicksort degrades.\n2. Merge divides evenly.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "P contains problems solvable in polynomial time.", "choices": null, "id": "cs_0229", "kind": "concept", "lang": "en", "question": "What is complexity class P?", "steps": ["Polynomial time.", "Efficiently solvable.", "Example: sorting."], "subject": "computer_science", "text": "Answer: Polynomial-time problems.\nSteps:\n1. Polynomial time.\n2. Efficiently solvable.\n3. Example: sorting.", "topic": "complexity"}
{"answer": "Prvek na indexu 1 je číslo 20.", "choices": null, "id": "cs_0230", "kind": "worked_example", "lang": "cs", "question": "Pole je [10,20,30]. Co je prvek na indexu 1?", "steps": ["Index 0 je 10.", "Index 1 je 20.", "Výsledek je 20."], "subject": "computer_science", "text": "Answer: 20.\nSteps:\n1. Index 0 je 10.\n2. Index 1 je 20.\n3. Výsledek je 20.", "topic": "data_structures"}
{"answer": "F-strings embed expressions as f'{x}' evaluated at runtime.", "choices": null, "id": "cs_0231", "kind": "concept", "lang": "en", "question": "What are Python f-strings?", "steps": ["Prefix f.", "Braces hold code.", "Rendered as text."], "subject": "computer_science", "text": "Answer: Embedded expressions.\nSteps:\n1. Prefix f.\n2. Braces hold code.\n3. Rendered as text.", "topic": "python"}
{"answer": "'abc'.toUpperCase() returns 'ABC'.", "choices": {"A": "'ABC'", "B": "'abc'", "C": "'Abc'", "D": "Error"}, "id": "cs_0232", "kind": "multiple_choice", "lang": "en", "question": "What does 'abc'.toUpperCase() return?", "steps": ["Capitalize all.", "Result ABC.", "Select option A."], "subject": "computer_science", "text": "Answer: 'ABC'.\nSteps:\n1. Capitalize all.\n2. Result ABC.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "SELECT 100 - 37 returns 63.", "choices": null, "id": "cs_0233", "kind": "worked_example", "lang": "en", "question": "What does SELECT 100 - 37 return?", "steps": ["Subtract 37.", "100 - 37 = 63.", "Result is 63."], "subject": "computer_science", "text": "Answer: 63.\nSteps:\n1. Subtract 37.\n2. 100 - 37 = 63.\n3. Result is 63.", "topic": "sql"}
{"answer": "A /25 network has 126 usable hosts.", "choices": null, "id": "cs_0234", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in a /25 network?", "steps": ["Host bits = 7.", "Addresses = 128.", "Usable = 128 - 2 = 126."], "subject": "computer_science", "text": "Answer: 126.\nSteps:\n1. Host bits = 7.\n2. Addresses = 128.\n3. Usable = 128 - 2 = 126.", "topic": "networking"}
{"answer": "SELECT DISTINCT odstraní duplicitní řádky.", "choices": {"A": "Odstraní duplicity", "B": "Seřadí řádky", "C": "Spojí tabulky", "D": "Smaže tabulku"}, "id": "cs_0235", "kind": "multiple_choice", "lang": "cs", "question": "Co dělá SELECT DISTINCT?", "steps": ["DISTINCT filtruje.", "Duplicity pryč.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Odstraní duplicity.\nSteps:\n1. DISTINCT filtruje.\n2. Duplicity pryč.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "Deadlock is circular waiting where each process holds a needed resource.", "choices": null, "id": "cs_0236", "kind": "concept", "lang": "en", "question": "What is a deadlock?", "steps": ["Each waits.", "Cycle of holders.", "Nothing proceeds."], "subject": "computer_science", "text": "Answer: Circular wait.\nSteps:\n1. Each waits.\n2. Cycle of holders.\n3. Nothing proceeds.", "topic": "operating_systems"}
{"answer": "B inherits x = 5 from A.", "choices": null, "id": "cs_0237", "kind": "worked_example", "lang": "en", "question": "Class A defines x = 5, B(A) inherits. What is B().x?", "steps": ["A sets x.", "B inherits A.", "B().x = 5."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. A sets x.\n2. B inherits A.\n3. B().x = 5.", "topic": "oop"}
{"answer": "Binary search on 8 items needs at most 3 comparisons.", "choices": {"A": "2", "B": "3", "C": "4", "D": "8"}, "id": "cs_0238", "kind": "multiple_choice", "lang": "en", "question": "What is worst-case binary search comparisons for n = 8?", "steps": ["log2(8) = 3.", "Halve thrice.", "Select option B."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. log2(8) = 3.\n2. Halve thrice.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "Space-time tradeoff exchanges memory for speed or vice versa.", "choices": null, "id": "cs_0239", "kind": "concept", "lang": "en", "question": "What is a space-time tradeoff?", "steps": ["More memory, less time.", "Or less memory, more time.", "Example: caching."], "subject": "computer_science", "text": "Answer: Memory versus speed.\nSteps:\n1. More memory, less time.\n2. Or less memory, more time.\n3. Example: caching.", "topic": "complexity"}
{"answer": "Minimum je v kořenu, tedy 3.", "choices": null, "id": "cs_0240", "kind": "worked_example", "lang": "cs", "question": "Min-halda je [3,5,4]. Kde je minimum?", "steps": ["Kořen je 3.", "Děti větší.", "Minimum je 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Kořen je 3.\n2. Děti větší.\n3. Minimum je 3.", "topic": "data_structures"}
{"answer": "Generators yield items lazily one at a time with yield.", "choices": null, "id": "cs_0241", "kind": "concept", "lang": "en", "question": "What is a Python generator?", "steps": ["Uses yield.", "Lazy iteration.", "Saves memory."], "subject": "computer_science", "text": "Answer: Lazy iterator.\nSteps:\n1. Uses yield.\n2. Lazy iteration.\n3. Saves memory.", "topic": "python"}
{"answer": "[] + [] is '' (empty string).", "choices": {"A": "''", "B": "0", "C": "[]", "D": "NaN"}, "id": "cs_0242", "kind": "multiple_choice", "lang": "en", "question": "What does [] + [] give in JavaScript?", "steps": ["Arrays to strings.", "'' + ''.", "Select option A."], "subject": "computer_science", "text": "Answer: ''.\nSteps:\n1. Arrays to strings.\n2. '' + ''.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "LENGTH('hello') is 5.", "choices": null, "id": "cs_0243", "kind": "worked_example", "lang": "en", "question": "What does SELECT LENGTH('hello') return?", "steps": ["Count letters.", "h-e-l-l-o = 5.", "Result = 5."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. Count letters.\n2. h-e-l-l-o = 5.\n3. Result = 5.", "topic": "sql"}
{"answer": "Payload is 1500 - 20 = 1480 bytes.", "choices": null, "id": "cs_0244", "kind": "worked_example", "lang": "en", "question": "Packet 1500 bytes, header 20. What is the payload size?", "steps": ["Total 1500.", "Minus header 20.", "Payload = 1480."], "subject": "computer_science", "text": "Answer: 1480.\nSteps:\n1. Total 1500.\n2. Minus header 20.\n3. Payload = 1480.", "topic": "networking"}
{"answer": "Data mění příkaz UPDATE.", "choices": {"A": "SELECT", "B": "UPDATE", "C": "JOIN", "D": "GROUP BY"}, "id": "cs_0245", "kind": "multiple_choice", "lang": "cs", "question": "Který příkaz mění existující data?", "steps": ["SELECT čte.", "UPDATE mění.", "Vyber možnost B."], "subject": "computer_science", "text": "Answer: UPDATE.\nSteps:\n1. SELECT čte.\n2. UPDATE mění.\n3. Vyber možnost B.\nAnswer: (B)", "topic": "databases"}
{"answer": "Paging splits memory into fixed-size pages and frames.", "choices": null, "id": "cs_0246", "kind": "concept", "lang": "en", "question": "What is paging?", "steps": ["Fixed blocks.", "Pages map to frames.", "Avoids fragmentation."], "subject": "computer_science", "text": "Answer: Fixed-size blocks.\nSteps:\n1. Fixed blocks.\n2. Pages map to frames.\n3. Avoids fragmentation.", "topic": "operating_systems"}
{"answer": "Area = 3.14 x 1 x 1 = 3.14.", "choices": null, "id": "cs_0247", "kind": "worked_example", "lang": "en", "question": "Circle radius 1, area = 3.14*r*r. What is the area?", "steps": ["r = 1.", "3.14 x 1 x 1.", "Area = 3.14."], "subject": "computer_science", "text": "Answer: 3.14.\nSteps:\n1. r = 1.\n2. 3.14 x 1 x 1.\n3. Area = 3.14.", "topic": "oop"}
{"answer": "Merge sort splits, sorts, and merges: divide and conquer.", "choices": {"A": "Merge sort", "B": "Bubble sort", "C": "Linear search", "D": "BFS"}, "id": "cs_0248", "kind": "multiple_choice", "lang": "en", "question": "Which is a divide-and-conquer algorithm?", "steps": ["Split problem.", "Merge solves.", "Select option A."], "subject": "computer_science", "text": "Answer: Merge sort.\nSteps:\n1. Split problem.\n2. Merge solves.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "Nested n x m loops cost O(n*m).", "choices": null, "id": "cs_0249", "kind": "concept", "lang": "en", "question": "What is the complexity of n x m nested loops?", "steps": ["Outer n.", "Inner m.", "Product n*m."], "subject": "computer_science", "text": "Answer: O(n*m).\nSteps:\n1. Outer n.\n2. Inner m.\n3. Product n*m.", "topic": "complexity"}
{"answer": "Seznam má 3 uzly.", "choices": null, "id": "cs_0250", "kind": "worked_example", "lang": "cs", "question": "Seznam je 1 -> 2 -> 3 -> None. Kolik má uzlů?", "steps": ["Počítej 1, 2, 3.", "Konec None.", "Celkem 3 uzly."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Počítej 1, 2, 3.\n2. Konec None.\n3. Celkem 3 uzly.", "topic": "data_structures"}
{"answer": "Exception handling catches errors with try/except/finally blocks.", "choices": null, "id": "cs_0251", "kind": "concept", "lang": "en", "question": "What is exception handling in Python?", "steps": ["Try risky code.", "Catch exceptions.", "Finally cleans up."], "subject": "computer_science", "text": "Answer: Catch errors safely.\nSteps:\n1. Try risky code.\n2. Catch exceptions.\n3. Finally cleans up.", "topic": "python"}
{"answer": "Default sort is lexicographic, so [10,2,1] sorts to 1,10,2.", "choices": {"A": "1,2,10", "B": "1,10,2", "C": "10,1,2", "D": "10,2,1"}, "id": "cs_0252", "kind": "multiple_choice", "lang": "en", "question": "What does [10,2,1].sort().join(',') give?", "steps": ["Default string sort.", "1 < 10 < 2.", "Select option B."], "subject": "computer_science", "text": "Answer: 1,10,2.\nSteps:\n1. Default string sort.\n2. 1 < 10 < 2.\n3. Select option B.\nAnswer: (B)", "topic": "javascript"}
{"answer": "SELECT 20 / 4 returns 5.", "choices": null, "id": "cs_0253", "kind": "worked_example", "lang": "en", "question": "What does SELECT 20 / 4 return?", "steps": ["Divide 20 by 4.", "20 / 4 = 5.", "Result is 5."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. Divide 20 by 4.\n2. 20 / 4 = 5.\n3. Result is 5.", "topic": "sql"}
{"answer": "A /27 network has 30 usable hosts.", "choices": null, "id": "cs_0254", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in a /27 network?", "steps": ["Host bits = 5.", "Addresses = 32.", "Usable = 32 - 2 = 30."], "subject": "computer_science", "text": "Answer: 30.\nSteps:\n1. Host bits = 5.\n2. Addresses = 32.\n3. Usable = 32 - 2 = 30.", "topic": "networking"}
{"answer": "Index zrychluje vyhledávání v tabulce.", "choices": {"A": "Zrychluje hledání", "B": "Maže data", "C": "Mění schéma", "D": "Vypíná databázi"}, "id": "cs_0255", "kind": "multiple_choice", "lang": "cs", "question": "Co je databázový index?", "steps": ["Index pomáhá.", "Hledání rychlejší.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Zrychluje hledání.\nSteps:\n1. Index pomáhá.\n2. Hledání rychlejší.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "A thread pool reuses a fixed set of threads for many tasks.", "choices": null, "id": "cs_0256", "kind": "concept", "lang": "en", "question": "What is a thread pool?", "steps": ["Create threads once.", "Queue tasks.", "Reuse workers."], "subject": "computer_science", "text": "Answer: Reused workers.\nSteps:\n1. Create threads once.\n2. Queue tasks.\n3. Reuse workers.", "topic": "operating_systems"}
{"answer": "Rectangle(6, 7).area() is 42.", "choices": null, "id": "cs_0257", "kind": "worked_example", "lang": "en", "question": "Rectangle 6 by 7, area = w*h. What is the area?", "steps": ["w = 6, h = 7.", "6 x 7 = 42.", "Area = 42."], "subject": "computer_science", "text": "Answer: 42.\nSteps:\n1. w = 6, h = 7.\n2. 6 x 7 = 42.\n3. Area = 42.", "topic": "oop"}
{"answer": "Kruskal builds a minimum spanning tree by adding cheapest edges.", "choices": {"A": "Kruskal", "B": "Bubble sort", "C": "Binary search", "D": "BFS"}, "id": "cs_0258", "kind": "multiple_choice", "lang": "en", "question": "Which finds a minimum spanning tree?", "steps": ["Need MST.", "Kruskal sorts edges.", "Select option A."], "subject": "computer_science", "text": "Answer: Kruskal.\nSteps:\n1. Need MST.\n2. Kruskal sorts edges.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "Logarithmic complexity halves work each step, like O(log n).", "choices": null, "id": "cs_0259", "kind": "concept", "lang": "en", "question": "What is logarithmic complexity?", "steps": ["Halve each step.", "Few steps for big n.", "Example: binary search."], "subject": "computer_science", "text": "Answer: Halving each step.\nSteps:\n1. Halve each step.\n2. Few steps for big n.\n3. Example: binary search.", "topic": "complexity"}
{"answer": "K4 má 4x3/2 = 6 hran.", "choices": null, "id": "cs_0260", "kind": "worked_example", "lang": "cs", "question": "Kolik hran má úplný graf K4?", "steps": ["Vzorec n(n-1)/2.", "4x3/2 = 6.", "Hran je 6."], "subject": "computer_science", "text": "Answer: 6.\nSteps:\n1. Vzorec n(n-1)/2.\n2. 4x3/2 = 6.\n3. Hran je 6.", "topic": "data_structures"}
{"answer": "Lambdas are anonymous one-line functions written as lambda x: expr.", "choices": null, "id": "cs_0261", "kind": "concept", "lang": "en", "question": "What are Python lambda functions?", "steps": ["No def needed.", "Single expression.", "Good for callbacks."], "subject": "computer_science", "text": "Answer: Anonymous functions.\nSteps:\n1. No def needed.\n2. Single expression.\n3. Good for callbacks.", "topic": "python"}
{"answer": "typeof null is 'object' due to a legacy quirk.", "choices": {"A": "object", "B": "null", "C": "undefined", "D": "number"}, "id": "cs_0262", "kind": "multiple_choice", "lang": "en", "question": "What is typeof null in JavaScript?", "steps": ["Legacy quirk.", "Returns object.", "Select option A."], "subject": "computer_science", "text": "Answer: object.\nSteps:\n1. Legacy quirk.\n2. Returns object.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "MAX of (3, 9, 5) is 9.", "choices": null, "id": "cs_0263", "kind": "worked_example", "lang": "en", "question": "What does SELECT MAX(x) give for x in (3,9,5)?", "steps": ["Compare values.", "Largest is 9.", "Result = 9."], "subject": "computer_science", "text": "Answer: 9.\nSteps:\n1. Compare values.\n2. Largest is 9.\n3. Result = 9.", "topic": "sql"}
{"answer": "25 MB over 100 Mbps takes 2 seconds.", "choices": null, "id": "cs_0264", "kind": "worked_example", "lang": "en", "question": "Link 100 Mbps, file 25 MB. How many seconds to transfer?", "steps": ["25 MB = 200 Mb.", "200 / 100 = 2.", "Time = 2 s."], "subject": "computer_science", "text": "Answer: 2 s.\nSteps:\n1. 25 MB = 200 Mb.\n2. 200 / 100 = 2.\n3. Time = 2 s.", "topic": "networking"}
{"answer": "A v ACID znamená atomicita.", "choices": {"A": "Atomicita", "B": "Konzistence", "C": "Izolace", "D": "Trvanlivost"}, "id": "cs_0265", "kind": "multiple_choice", "lang": "cs", "question": "Co znamená A v ACID?", "steps": ["ACID vlastnosti.", "A je atomicita.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Atomicita.\nSteps:\n1. ACID vlastnosti.\n2. A je atomicita.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "A semaphore is a counter controlling access to shared resources.", "choices": null, "id": "cs_0266", "kind": "concept", "lang": "en", "question": "What is a semaphore?", "steps": ["Counter starts at N.", "Wait decrements.", "Signal increments."], "subject": "computer_science", "text": "Answer: Access counter.\nSteps:\n1. Counter starts at N.\n2. Wait decrements.\n3. Signal increments.", "topic": "operating_systems"}
{"answer": "Counter at 10 after dec() is 9.", "choices": null, "id": "cs_0267", "kind": "worked_example", "lang": "en", "question": "Counter value 10, dec() subtracts 1. What is the value?", "steps": ["Start 10.", "Minus 1.", "Value = 9."], "subject": "computer_science", "text": "Answer: 9.\nSteps:\n1. Start 10.\n2. Minus 1.\n3. Value = 9.", "topic": "oop"}
{"answer": "Quicksort picks a pivot and partitions around it.", "choices": {"A": "Pivot", "B": "Root", "C": "Hash", "D": "Queue"}, "id": "cs_0268", "kind": "multiple_choice", "lang": "en", "question": "What does quicksort pick to partition?", "steps": ["Choose pivot.", "Partition around.", "Select option A."], "subject": "computer_science", "text": "Answer: Pivot.\nSteps:\n1. Choose pivot.\n2. Partition around.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "Best-case analysis measures minimum cost over inputs of size n.", "choices": null, "id": "cs_0269", "kind": "concept", "lang": "en", "question": "What is best-case analysis?", "steps": ["Easiest input.", "Minimum cost.", "Rarely relied on."], "subject": "computer_science", "text": "Answer: Minimum cost.\nSteps:\n1. Easiest input.\n2. Minimum cost.\n3. Rarely relied on.", "topic": "complexity"}
{"answer": "Load factor je 9/12 = 0.75.", "choices": null, "id": "cs_0270", "kind": "worked_example", "lang": "cs", "question": "9 prvků ve 12 slotech. Jaký je load factor?", "steps": ["9 / 12.", "Výpočet 0.75.", "Load factor = 0.75."], "subject": "computer_science", "text": "Answer: 0.75.\nSteps:\n1. 9 / 12.\n2. Výpočet 0.75.\n3. Load factor = 0.75.", "topic": "data_structures"}
{"answer": "The GIL allows only one thread to run Python bytecode at once.", "choices": null, "id": "cs_0271", "kind": "concept", "lang": "en", "question": "What is the Python GIL?", "steps": ["Global lock.", "One bytecode thread.", "Limits CPU parallelism."], "subject": "computer_science", "text": "Answer: Global interpreter lock.\nSteps:\n1. Global lock.\n2. One bytecode thread.\n3. Limits CPU parallelism.", "topic": "python"}
{"answer": "'hi'.length is 2.", "choices": {"A": "1", "B": "2", "C": "3", "D": "0"}, "id": "cs_0272", "kind": "multiple_choice", "lang": "en", "question": "What does 'hi'.length give?", "steps": ["Two letters.", "Length 2.", "Select option B."], "subject": "computer_science", "text": "Answer: 2.\nSteps:\n1. Two letters.\n2. Length 2.\n3. Select option B.\nAnswer: (B)", "topic": "javascript"}
{"answer": "MIN of (8, 3, 6) is 3.", "choices": null, "id": "cs_0273", "kind": "worked_example", "lang": "en", "question": "What does SELECT MIN(x) give for x in (8,3,6)?", "steps": ["Compare values.", "Smallest is 3.", "Result = 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Compare values.\n2. Smallest is 3.\n3. Result = 3.", "topic": "sql"}
{"answer": "A /28 network has 14 usable hosts.", "choices": null, "id": "cs_0274", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in a /28 network?", "steps": ["Host bits = 4.", "Addresses = 16.", "Usable = 16 - 2 = 14."], "subject": "computer_science", "text": "Answer: 14.\nSteps:\n1. Host bits = 4.\n2. Addresses = 16.\n3. Usable = 16 - 2 = 14.", "topic": "networking"}
{"answer": "ORDER BY třídí výsledné řádky.", "choices": {"A": "Třídí řádky", "B": "Filtruje řádky", "C": "Spojuje tabulky", "D": "Maže řádky"}, "id": "cs_0275", "kind": "multiple_choice", "lang": "cs", "question": "Co dělá ORDER BY?", "steps": ["ORDER BY řadí.", "Podle sloupců.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Třídí řádky.\nSteps:\n1. ORDER BY řadí.\n2. Podle sloupců.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "A zombie process has terminated but its parent has not reaped it yet.", "choices": null, "id": "cs_0276", "kind": "concept", "lang": "en", "question": "What is a zombie process?", "steps": ["Child exits.", "Parent delays wait.", "Entry lingers."], "subject": "computer_science", "text": "Answer: Exited but unreaped.\nSteps:\n1. Child exits.\n2. Parent delays wait.\n3. Entry lingers.", "topic": "operating_systems"}
{"answer": "Balance 200 minus 70 leaves 130.", "choices": null, "id": "cs_0277", "kind": "worked_example", "lang": "en", "question": "Account balance 200, withdraw(70). What is the balance?", "steps": ["Start 200.", "Subtract 70.", "Balance = 130."], "subject": "computer_science", "text": "Answer: 130.\nSteps:\n1. Start 200.\n2. Subtract 70.\n3. Balance = 130.", "topic": "oop"}
{"answer": "Huffman coding greedily merges the two least frequent symbols.", "choices": {"A": "Huffman coding", "B": "Bubble sort", "C": "Binary search", "D": "DFS"}, "id": "cs_0278", "kind": "multiple_choice", "lang": "en", "question": "Which is a greedy algorithm?", "steps": ["Greedy picks best now.", "Huffman merges least.", "Select option A."], "subject": "computer_science", "text": "Answer: Huffman coding.\nSteps:\n1. Greedy picks best now.\n2. Huffman merges least.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "NP contains problems verifiable in polynomial time.", "choices": null, "id": "cs_0279", "kind": "concept", "lang": "en", "question": "What is complexity class NP?", "steps": ["Check solutions fast.", "Finding may be hard.", "Example: SAT."], "subject": "computer_science", "text": "Answer: Fast to verify.\nSteps:\n1. Check solutions fast.\n2. Finding may be hard.\n3. Example: SAT.", "topic": "complexity"}
{"answer": "Po dvou operacích dequeue zbude jen 9.", "choices": null, "id": "cs_0280", "kind": "worked_example", "lang": "cs", "question": "Fronta je 7, 8, 9. Co zbude po dvou dequeue?", "steps": ["Odeber 7.", "Odeber 8.", "Zbude 9."], "subject": "computer_science", "text": "Answer: 9.\nSteps:\n1. Odeber 7.\n2. Odeber 8.\n3. Zbude 9.", "topic": "data_structures"}
{"answer": "Sets store unordered unique items with fast membership tests.", "choices": null, "id": "cs_0281", "kind": "concept", "lang": "en", "question": "What are Python sets?", "steps": ["No duplicates.", "Unordered.", "Fast in-checks."], "subject": "computer_science", "text": "Answer: Unique unordered items.\nSteps:\n1. No duplicates.\n2. Unordered.\n3. Fast in-checks.", "topic": "python"}
{"answer": "Boolean(0) is false.", "choices": {"A": "true", "B": "false", "C": "0", "D": "undefined"}, "id": "cs_0282", "kind": "multiple_choice", "lang": "en", "question": "What does Boolean(0) give?", "steps": ["0 is falsy.", "Coerces to false.", "Select option B."], "subject": "computer_science", "text": "Answer: false.\nSteps:\n1. 0 is falsy.\n2. Coerces to false.\n3. Select option B.\nAnswer: (B)", "topic": "javascript"}
{"answer": "3 + 4 * 2 equals 11 by precedence.", "choices": null, "id": "cs_0283", "kind": "worked_example", "lang": "en", "question": "What does SELECT 3 + 4 * 2 return?", "steps": ["Multiply first: 8.", "Add 3.", "Result = 11."], "subject": "computer_science", "text": "Answer: 11.\nSteps:\n1. Multiply first: 8.\n2. Add 3.\n3. Result = 11.", "topic": "sql"}
{"answer": "A /29 network has 6 usable hosts.", "choices": null, "id": "cs_0284", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in a /29 network?", "steps": ["Host bits = 3.", "Addresses = 8.", "Usable = 8 - 2 = 6."], "subject": "computer_science", "text": "Answer: 6.\nSteps:\n1. Host bits = 3.\n2. Addresses = 8.\n3. Usable = 8 - 2 = 6.", "topic": "networking"}
{"answer": "GROUP BY seskupuje řádky se stejnou hodnotou.", "choices": {"A": "Seskupuje řádky", "B": "Třídí řádky", "C": "Maže řádky", "D": "Vytváří tabulku"}, "id": "cs_0285", "kind": "multiple_choice", "lang": "cs", "question": "Co dělá GROUP BY?", "steps": ["Stejné hodnoty.", "Skupiny pro agregaci.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Seskupuje řádky.\nSteps:\n1. Stejné hodnoty.\n2. Skupiny pro agregaci.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "Swapping moves processes between RAM and disk to free memory.", "choices": null, "id": "cs_0286", "kind": "concept", "lang": "en", "question": "What is swapping?", "steps": ["RAM is full.", "Move process to disk.", "Bring back later."], "subject": "computer_science", "text": "Answer: RAM-disk exchange.\nSteps:\n1. RAM is full.\n2. Move process to disk.\n3. Bring back later.", "topic": "operating_systems"}
{"answer": "Point(3, 4).sum() is 7.", "choices": null, "id": "cs_0287", "kind": "worked_example", "lang": "en", "question": "Point stores x, y with sum = x+y. What is Point(3,4).sum()?", "steps": ["x = 3, y = 4.", "3 + 4 = 7.", "Sum = 7."], "subject": "computer_science", "text": "Answer: 7.\nSteps:\n1. x = 3, y = 4.\n2. 3 + 4 = 7.\n3. Sum = 7.", "topic": "oop"}
{"answer": "Inorder traversal of a BST visits keys in sorted order.", "choices": {"A": "Sorted", "B": "Reverse", "C": "Random", "D": "Level"}, "id": "cs_0288", "kind": "multiple_choice", "lang": "en", "question": "What order does BST inorder give?", "steps": ["Left, root, right.", "Ascending keys.", "Select option A."], "subject": "computer_science", "text": "Answer: Sorted.\nSteps:\n1. Left, root, right.\n2. Ascending keys.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "Constant time O(1) costs the same regardless of input size.", "choices": null, "id": "cs_0289", "kind": "concept", "lang": "en", "question": "What is constant time complexity?", "steps": ["Fixed steps.", "No growth.", "Example: array index."], "subject": "computer_science", "text": "Answer: Fixed cost.\nSteps:\n1. Fixed steps.\n2. No growth.\n3. Example: array index.", "topic": "complexity"}
{"answer": "Po dvou pop zbude jen 1.", "choices": null, "id": "cs_0290", "kind": "worked_example", "lang": "cs", "question": "Zásobník je 1, 2, 3. Co zbude po dvou pop?", "steps": ["Odeber 3.", "Odeber 2.", "Zbude 1."], "subject": "computer_science", "text": "Answer: 1.\nSteps:\n1. Odeber 3.\n2. Odeber 2.\n3. Zbude 1.", "topic": "data_structures"}
{"answer": "Decorators wrap functions using @name above a definition.", "choices": null, "id": "cs_0291", "kind": "concept", "lang": "en", "question": "What is a Python decorator?", "steps": ["@ above def.", "Wraps function.", "Adds behavior."], "subject": "computer_science", "text": "Answer: Function wrapper.\nSteps:\n1. @ above def.\n2. Wraps function.\n3. Adds behavior.", "topic": "python"}
{"answer": "'5' + 2 is '52' because plus concatenates strings.", "choices": {"A": "'52'", "B": "7", "C": "5", "D": "NaN"}, "id": "cs_0292", "kind": "multiple_choice", "lang": "en", "question": "What does '5' + 2 give in JavaScript?", "steps": ["Plus prefers string.", "Concat 5 and 2.", "Select option A."], "subject": "computer_science", "text": "Answer: '52'.\nSteps:\n1. Plus prefers string.\n2. Concat 5 and 2.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "UPPER('hi') returns 'HI'.", "choices": null, "id": "cs_0293", "kind": "worked_example", "lang": "en", "question": "What does SELECT UPPER('hi') return?", "steps": ["Capitalize letters.", "hi becomes HI.", "Result = 'HI'."], "subject": "computer_science", "text": "Answer: 'HI'.\nSteps:\n1. Capitalize letters.\n2. hi becomes HI.\n3. Result = 'HI'.", "topic": "sql"}
{"answer": "The /16 mask is 255.255.0.0.", "choices": null, "id": "cs_0294", "kind": "worked_example", "lang": "en", "question": "What is the subnet mask for /16?", "steps": ["16 ones.", "Two octets full.", "Mask = 255.255.0.0."], "subject": "computer_science", "text": "Answer: 255.255.0.0.\nSteps:\n1. 16 ones.\n2. Two octets full.\n3. Mask = 255.255.0.0.", "topic": "networking"}
{"answer": "HAVING filtruje skupiny po agregaci.", "choices": {"A": "Filtruje skupiny", "B": "Třídí řádky", "C": "Maže řádky", "D": "Spojuje tabulky"}, "id": "cs_0295", "kind": "multiple_choice", "lang": "cs", "question": "Co dělá HAVING?", "steps": ["Po GROUP BY.", "Filtr agregací.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Filtruje skupiny.\nSteps:\n1. Po GROUP BY.\n2. Filtr agregací.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "CPU scheduling decides which ready process runs next.", "choices": null, "id": "cs_0296", "kind": "concept", "lang": "en", "question": "What is CPU scheduling?", "steps": ["Many ready tasks.", "Pick one.", "Switch on events."], "subject": "computer_science", "text": "Answer: Pick next process.\nSteps:\n1. Many ready tasks.\n2. Pick one.\n3. Switch on events.", "topic": "operating_systems"}
{"answer": "120 pages minus 30 read leaves 90.", "choices": null, "id": "cs_0297", "kind": "worked_example", "lang": "en", "question": "Book has 120 pages, read 30. How many remain?", "steps": ["Total 120.", "Minus 30.", "Remain = 90."], "subject": "computer_science", "text": "Answer: 90.\nSteps:\n1. Total 120.\n2. Minus 30.\n3. Remain = 90.", "topic": "oop"}
{"answer": "Binary search requires sorted input to halve correctly.", "choices": {"A": "Linear", "B": "Binary", "C": "BFS", "D": "DFS"}, "id": "cs_0298", "kind": "multiple_choice", "lang": "en", "question": "Which search needs sorted input?", "steps": ["Halving assumes order.", "Binary needs sorted.", "Select option B."], "subject": "computer_science", "text": "Answer: Binary.\nSteps:\n1. Halving assumes order.\n2. Binary needs sorted.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "Quadratic O(n^2) grows with the square, typical of nested loops.", "choices": null, "id": "cs_0299", "kind": "concept", "lang": "en", "question": "What is quadratic complexity?", "steps": ["n by n work.", "Grows fast.", "Example: bubble sort."], "subject": "computer_science", "text": "Answer: Square growth.\nSteps:\n1. n by n work.\n2. Grows fast.\n3. Example: bubble sort.", "topic": "complexity"}
{"answer": "Inorder dá 5, 10, 15.", "choices": null, "id": "cs_0300", "kind": "worked_example", "lang": "cs", "question": "Kořen 10, levý 5, pravý 15. Co dá inorder?", "steps": ["Levý 5.", "Kořen 10.", "Pravý 15."], "subject": "computer_science", "text": "Answer: 5, 10, 15.\nSteps:\n1. Levý 5.\n2. Kořen 10.\n3. Pravý 15.", "topic": "data_structures"}
{"answer": "Keyword arguments are named parameters with defaults passed as name=value.", "choices": null, "id": "cs_0301", "kind": "concept", "lang": "en", "question": "What are keyword arguments in Python?", "steps": ["Define def f(a=1).", "Call f(a=2).", "Order flexible."], "subject": "computer_science", "text": "Answer: Named parameters.\nSteps:\n1. Define def f(a=1).\n2. Call f(a=2).\n3. Order flexible.", "topic": "python"}
{"answer": "[1,2,3].includes(2) is true.", "choices": {"A": "true", "B": "false", "C": "2", "D": "undefined"}, "id": "cs_0302", "kind": "multiple_choice", "lang": "en", "question": "What does [1,2,3].includes(2) give?", "steps": ["Search for 2.", "Found.", "Select option A."], "subject": "computer_science", "text": "Answer: true.\nSteps:\n1. Search for 2.\n2. Found.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "SELECT 9 * 9 returns 81.", "choices": null, "id": "cs_0303", "kind": "worked_example", "lang": "en", "question": "What does SELECT 9 * 9 return?", "steps": ["Multiply 9 by 9.", "9 x 9 = 81.", "Result is 81."], "subject": "computer_science", "text": "Answer: 81.\nSteps:\n1. Multiply 9 by 9.\n2. 9 x 9 = 81.\n3. Result is 81.", "topic": "sql"}
{"answer": "A /23 network has 510 usable hosts.", "choices": null, "id": "cs_0304", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in a /23 network?", "steps": ["Host bits = 9.", "Addresses = 512.", "Usable = 512 - 2 = 510."], "subject": "computer_science", "text": "Answer: 510.\nSteps:\n1. Host bits = 9.\n2. Addresses = 512.\n3. Usable = 512 - 2 = 510.", "topic": "networking"}
{"answer": "Řádky filtruje klauzule WHERE.", "choices": {"A": "WHERE", "B": "ORDER BY", "C": "GROUP BY", "D": "JOIN"}, "id": "cs_0305", "kind": "multiple_choice", "lang": "cs", "question": "Která klauzule filtruje řádky?", "steps": ["WHERE omezuje.", "Před agregací.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: WHERE.\nSteps:\n1. WHERE omezuje.\n2. Před agregací.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "Multitasking runs multiple processes concurrently by rapid switching.", "choices": null, "id": "cs_0306", "kind": "concept", "lang": "en", "question": "What is multitasking?", "steps": ["Many processes.", "CPU switches fast.", "Appears parallel."], "subject": "computer_science", "text": "Answer: Concurrent processes.\nSteps:\n1. Many processes.\n2. CPU switches fast.\n3. Appears parallel.", "topic": "operating_systems"}
{"answer": "5000 salary plus 500 bonus is 5500.", "choices": null, "id": "cs_0307", "kind": "worked_example", "lang": "en", "question": "Employee salary 5000, bonus 500. What is total pay?", "steps": ["Base 5000.", "Add 500.", "Total = 5500."], "subject": "computer_science", "text": "Answer: 5500.\nSteps:\n1. Base 5000.\n2. Add 500.\n3. Total = 5500.", "topic": "oop"}
{"answer": "Bellman-Ford handles negative edges for single-source shortest paths.", "choices": {"A": "Dijkstra", "B": "Bellman-Ford", "C": "Bubble sort", "D": "DFS"}, "id": "cs_0308", "kind": "multiple_choice", "lang": "en", "question": "Which handles negative edges for shortest paths?", "steps": ["Dijkstra needs non-negative.", "Bellman-Ford relaxes.", "Select option B."], "subject": "computer_science", "text": "Answer: Bellman-Ford.\nSteps:\n1. Dijkstra needs non-negative.\n2. Bellman-Ford relaxes.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "Linear O(n) cost grows proportionally with input size.", "choices": null, "id": "cs_0309", "kind": "concept", "lang": "en", "question": "What is linear complexity?", "steps": ["One pass.", "Double input, double time.", "Example: linear search."], "subject": "computer_science", "text": "Answer: Proportional growth.\nSteps:\n1. One pass.\n2. Double input, double time.\n3. Example: linear search.", "topic": "complexity"}
{"answer": "Délka pole je 4.", "choices": null, "id": "cs_0310", "kind": "worked_example", "lang": "cs", "question": "Pole je [5,6,7,8]. Jaká je délka?", "steps": ["Počítej prvky.", "5, 6, 7, 8.", "Délka = 4."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Počítej prvky.\n2. 5, 6, 7, 8.\n3. Délka = 4.", "topic": "data_structures"}
{"answer": "== compares values while is compares object identity.", "choices": null, "id": "cs_0311", "kind": "concept", "lang": "en", "question": "How do == and is differ in Python?", "steps": ["== checks equality.", "is checks identity.", "Small ints may share."], "subject": "computer_science", "text": "Answer: Value versus identity.\nSteps:\n1. == checks equality.\n2. is checks identity.\n3. Small ints may share.", "topic": "python"}
{"answer": "0 == false is true under loose equality.", "choices": {"A": "true", "B": "false", "C": "0", "D": "TypeError"}, "id": "cs_0312", "kind": "multiple_choice", "lang": "en", "question": "What does 0 == false give in JavaScript?", "steps": ["Loose coercion.", "0 equals false.", "Select option A."], "subject": "computer_science", "text": "Answer: true.\nSteps:\n1. Loose coercion.\n2. 0 equals false.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "10 % 3 returns 1.", "choices": null, "id": "cs_0313", "kind": "worked_example", "lang": "en", "question": "What does SELECT 10 % 3 return?", "steps": ["Divide 10 by 3.", "Remainder 1.", "Result = 1."], "subject": "computer_science", "text": "Answer: 1.\nSteps:\n1. Divide 10 by 3.\n2. Remainder 1.\n3. Result = 1.", "topic": "sql"}
{"answer": "40 ms round-trip allows 25 serial requests per second.", "choices": null, "id": "cs_0314", "kind": "worked_example", "lang": "en", "question": "Round-trip 40 ms. How many serial requests per second?", "steps": ["1000 ms per second.", "1000 / 40 = 25.", "Rate = 25."], "subject": "computer_science", "text": "Answer: 25.\nSteps:\n1. 1000 ms per second.\n2. 1000 / 40 = 25.\n3. Rate = 25.", "topic": "networking"}
{"answer": "JOIN spojuje řádky ze dvou tabulek.", "choices": {"A": "Spojuje tabulky", "B": "Maže řádky", "C": "Třídí řádky", "D": "Filtruje řádky"}, "id": "cs_0315", "kind": "multiple_choice", "lang": "cs", "question": "Co dělá JOIN?", "steps": ["Dvě tabulky.", "Spojení podle klíče.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Spojuje tabulky.\nSteps:\n1. Dvě tabulky.\n2. Spojení podle klíče.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "A file descriptor is an integer handle for an open file.", "choices": null, "id": "cs_0316", "kind": "concept", "lang": "en", "question": "What is a file descriptor?", "steps": ["Open returns number.", "Read/write use it.", "Close frees it."], "subject": "computer_science", "text": "Answer: Open-file handle.\nSteps:\n1. Open returns number.\n2. Read/write use it.\n3. Close frees it.", "topic": "operating_systems"}
{"answer": "60 plus 20 gives speed 80.", "choices": null, "id": "cs_0317", "kind": "worked_example", "lang": "en", "question": "Car speed 60, accelerate(20). What is the speed?", "steps": ["Start 60.", "Add 20.", "Speed = 80."], "subject": "computer_science", "text": "Answer: 80.\nSteps:\n1. Start 60.\n2. Add 20.\n3. Speed = 80.", "topic": "oop"}
{"answer": "Memoization caches function results to avoid recomputation.", "choices": {"A": "Caches results", "B": "Sorts data", "C": "Encrypts data", "D": "Compresses data"}, "id": "cs_0318", "kind": "multiple_choice", "lang": "en", "question": "What does memoization do?", "steps": ["Store outputs.", "Reuse on repeat.", "Select option A."], "subject": "computer_science", "text": "Answer: Caches results.\nSteps:\n1. Store outputs.\n2. Reuse on repeat.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "Factorial O(n!) grows with permutations, exploding beyond n = 12.", "choices": null, "id": "cs_0319", "kind": "concept", "lang": "en", "question": "What is factorial complexity?", "steps": ["n! orderings.", "Huge growth.", "Example: TSP brute force."], "subject": "computer_science", "text": "Answer: Permutation growth.\nSteps:\n1. n! orderings.\n2. Huge growth.\n3. Example: TSP brute force.", "topic": "complexity"}
{"answer": "Do K4 chybí 3 hrany.", "choices": null, "id": "cs_0320", "kind": "worked_example", "lang": "cs", "question": "Graf má 4 vrcholy a 3 hrany. Kolik chybí do K4?", "steps": ["K4 má 6 hran.", "Máme 3.", "Chybí 6 - 3 = 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. K4 má 6 hran.\n2. Máme 3.\n3. Chybí 6 - 3 = 3.", "topic": "data_structures"}
{"answer": "*args collects extra positional arguments into a tuple.", "choices": null, "id": "cs_0321", "kind": "concept", "lang": "en", "question": "What does *args do in Python?", "steps": ["Variable inputs.", "Tuple inside.", "Loop over them."], "subject": "computer_science", "text": "Answer: Variable arguments.\nSteps:\n1. Variable inputs.\n2. Tuple inside.\n3. Loop over them.", "topic": "python"}
{"answer": "typeof 42 is 'number'.", "choices": {"A": "number", "B": "string", "C": "object", "D": "undefined"}, "id": "cs_0322", "kind": "multiple_choice", "lang": "en", "question": "What is typeof 42?", "steps": ["42 is numeric.", "Type number.", "Select option A."], "subject": "computer_science", "text": "Answer: number.\nSteps:\n1. 42 is numeric.\n2. Type number.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "LOWER('ABC') returns 'abc'.", "choices": null, "id": "cs_0323", "kind": "worked_example", "lang": "en", "question": "What does SELECT LOWER('ABC') return?", "steps": ["Lowercase each.", "ABC to abc.", "Result = 'abc'."], "subject": "computer_science", "text": "Answer: 'abc'.\nSteps:\n1. Lowercase each.\n2. ABC to abc.\n3. Result = 'abc'.", "topic": "sql"}
{"answer": "A /20 network has 4094 usable hosts.", "choices": null, "id": "cs_0324", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in a /20 network?", "steps": ["Host bits = 12.", "Addresses = 4096.", "Usable = 4096 - 2 = 4094."], "subject": "computer_science", "text": "Answer: 4094.\nSteps:\n1. Host bits = 12.\n2. Addresses = 4096.\n3. Usable = 4096 - 2 = 4094.", "topic": "networking"}
{"answer": "Schéma je struktura tabulek a vztahů.", "choices": {"A": "Struktura databáze", "B": "Konkrétní data", "C": "Index", "D": "Dotaz"}, "id": "cs_0325", "kind": "multiple_choice", "lang": "cs", "question": "Co je databázové schéma?", "steps": ["Popis struktury.", "Tabulky a typy.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Struktura databáze.\nSteps:\n1. Popis struktury.\n2. Tabulky a typy.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "A shell is a command interpreter between user and kernel.", "choices": null, "id": "cs_0326", "kind": "concept", "lang": "en", "question": "What is a shell?", "steps": ["Reads commands.", "Runs programs.", "Shows output."], "subject": "computer_science", "text": "Answer: Command interpreter.\nSteps:\n1. Reads commands.\n2. Runs programs.\n3. Shows output.", "topic": "operating_systems"}
{"answer": "Off toggled becomes on.", "choices": null, "id": "cs_0327", "kind": "worked_example", "lang": "en", "question": "Light is off, toggle() flips state. What is the state?", "steps": ["Start off.", "Flip.", "State = on."], "subject": "computer_science", "text": "Answer: on.\nSteps:\n1. Start off.\n2. Flip.\n3. State = on.", "topic": "oop"}
{"answer": "BFS visits level by level.", "choices": {"A": "DFS", "B": "BFS", "C": "Inorder", "D": "Postorder"}, "id": "cs_0328", "kind": "multiple_choice", "lang": "en", "question": "Which traversal is level order?", "steps": ["Level by level.", "Queue-based BFS.", "Select option B."], "subject": "computer_science", "text": "Answer: BFS.\nSteps:\n1. Level by level.\n2. Queue-based BFS.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "Average-case analysis measures expected cost over an input distribution.", "choices": null, "id": "cs_0329", "kind": "concept", "lang": "en", "question": "What is average-case analysis?", "steps": ["Assume distribution.", "Average costs.", "Example: quicksort."], "subject": "computer_science", "text": "Answer: Expected cost.\nSteps:\n1. Assume distribution.\n2. Average costs.\n3. Example: quicksort.", "topic": "complexity"}
{"answer": "Klíč 23 patří na slot 3.", "choices": null, "id": "cs_0330", "kind": "worked_example", "lang": "cs", "question": "Hash tabulka má 10 slotů. Kam patří klíč 23?", "steps": ["23 % 10 = 3.", "Slot 3.", "Výsledek je 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. 23 % 10 = 3.\n2. Slot 3.\n3. Výsledek je 3.", "topic": "data_structures"}
{"answer": "**kwargs collects extra keyword arguments into a dict.", "choices": null, "id": "cs_0331", "kind": "concept", "lang": "en", "question": "What does **kwargs do in Python?", "steps": ["Named extras.", "Dict inside.", "Access by key."], "subject": "computer_science", "text": "Answer: Named extras dict.\nSteps:\n1. Named extras.\n2. Dict inside.\n3. Access by key.", "topic": "python"}
{"answer": "'a,b,c'.split(',') has length 3.", "choices": {"A": "1", "B": "2", "C": "3", "D": "0"}, "id": "cs_0332", "kind": "multiple_choice", "lang": "en", "question": "What does 'a,b,c'.split(',').length give?", "steps": ["Split into 3.", "Length counts.", "Select option C."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Split into 3.\n2. Length counts.\n3. Select option C.\nAnswer: (C)", "topic": "javascript"}
{"answer": "SELECT 5 + 5 + 5 returns 15.", "choices": null, "id": "cs_0333", "kind": "worked_example", "lang": "en", "question": "What does SELECT 5 + 5 + 5 return?", "steps": ["Add first two: 10.", "Add 5.", "Result = 15."], "subject": "computer_science", "text": "Answer: 15.\nSteps:\n1. Add first two: 10.\n2. Add 5.\n3. Result = 15.", "topic": "sql"}
{"answer": "A /22 network has 1022 usable hosts.", "choices": null, "id": "cs_0334", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in a /22 network?", "steps": ["Host bits = 10.", "Addresses = 1024.", "Usable = 1024 - 2 = 1022."], "subject": "computer_science", "text": "Answer: 1022.\nSteps:\n1. Host bits = 10.\n2. Addresses = 1024.\n3. Usable = 1024 - 2 = 1022.", "topic": "networking"}
{"answer": "VIEW je uložený dotaz vystupující jako tabulka.", "choices": {"A": "Uložený dotaz", "B": "Fyzická tabulka", "C": "Index", "D": "Klíč"}, "id": "cs_0335", "kind": "multiple_choice", "lang": "cs", "question": "Co je pohled (VIEW)?", "steps": ["Dotaz uložen.", "Chová se jako tabulka.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Uložený dotaz.\nSteps:\n1. Dotaz uložen.\n2. Chová se jako tabulka.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "A device driver is software that controls a hardware device.", "choices": null, "id": "cs_0336", "kind": "concept", "lang": "en", "question": "What is a device driver?", "steps": ["Talks to hardware.", "Exposes interface.", "Kernel loads it."], "subject": "computer_science", "text": "Answer: Hardware control software.\nSteps:\n1. Talks to hardware.\n2. Exposes interface.\n3. Kernel loads it.", "topic": "operating_systems"}
{"answer": "100 plus 25 is 125.", "choices": null, "id": "cs_0337", "kind": "worked_example", "lang": "en", "question": "Player score 100, add(25). What is the score?", "steps": ["Start 100.", "Add 25.", "Score = 125."], "subject": "computer_science", "text": "Answer: 125.\nSteps:\n1. Start 100.\n2. Add 25.\n3. Score = 125.", "topic": "oop"}
{"answer": "Topological sort needs a directed acyclic graph.", "choices": {"A": "DAG", "B": "Cyclic graph", "C": "Unsorted list", "D": "Stack"}, "id": "cs_0338", "kind": "multiple_choice", "lang": "en", "question": "Which graph allows topological sort?", "steps": ["No cycles allowed.", "DAG works.", "Select option A."], "subject": "computer_science", "text": "Answer: DAG.\nSteps:\n1. No cycles allowed.\n2. DAG works.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "Linearithmic O(n log n) is typical of efficient sorts.", "choices": null, "id": "cs_0339", "kind": "concept", "lang": "en", "question": "What is linearithmic complexity?", "steps": ["n times log n.", "Efficient sorting.", "Example: merge sort."], "subject": "computer_science", "text": "Answer: n log n growth.\nSteps:\n1. n times log n.\n2. Efficient sorting.\n3. Example: merge sort.", "topic": "complexity"}
{"answer": "Maximum je 4 kroky.", "choices": null, "id": "cs_0340", "kind": "worked_example", "lang": "cs", "question": "Binární vyhledávání v 16 prvcích. Kolik kroků maximálně?", "steps": ["log2(16) = 4.", "Půlení čtyřikrát.", "Maximum 4 kroky."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. log2(16) = 4.\n2. Půlení čtyřikrát.\n3. Maximum 4 kroky.", "topic": "data_structures"}
{"answer": "Modules are .py files with reusable definitions imported elsewhere.", "choices": null, "id": "cs_0341", "kind": "concept", "lang": "en", "question": "What are Python modules?", "steps": ["File with code.", "Import it.", "Reuse functions."], "subject": "computer_science", "text": "Answer: Reusable files.\nSteps:\n1. File with code.\n2. Import it.\n3. Reuse functions.", "topic": "python"}
{"answer": "Math.floor(3.9) is 3.", "choices": {"A": "3", "B": "4", "C": "3.9", "D": "NaN"}, "id": "cs_0342", "kind": "multiple_choice", "lang": "en", "question": "What does Math.floor(3.9) give?", "steps": ["Round down.", "3.9 to 3.", "Select option A."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Round down.\n2. 3.9 to 3.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "ABS(-7) returns 7.", "choices": null, "id": "cs_0343", "kind": "worked_example", "lang": "en", "question": "What does SELECT ABS(-7) return?", "steps": ["Absolute value.", "Remove sign.", "Result = 7."], "subject": "computer_science", "text": "Answer: 7.\nSteps:\n1. Absolute value.\n2. Remove sign.\n3. Result = 7.", "topic": "sql"}
{"answer": "Broadcast for 192.168.1.0/24 is 192.168.1.255.", "choices": null, "id": "cs_0344", "kind": "worked_example", "lang": "en", "question": "What is the broadcast for 192.168.1.0/24?", "steps": ["Last octet host.", "All ones = 255.", "Broadcast .255."], "subject": "computer_science", "text": "Answer: 192.168.1.255.\nSteps:\n1. Last octet host.\n2. All ones = 255.\n3. Broadcast .255.", "topic": "networking"}
{"answer": "COUNT(*) počítá řádky.", "choices": {"A": "Počítá řádky", "B": "Maže řádky", "C": "Třídí řádky", "D": "Spojuje tabulky"}, "id": "cs_0345", "kind": "multiple_choice", "lang": "cs", "question": "Co dělá COUNT(*)?", "steps": ["Agregace počtu.", "Všechny řádky.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Počítá řádky.\nSteps:\n1. Agregace počtu.\n2. Všechny řádky.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "IPC lets processes exchange data via pipes, sockets, or shared memory.", "choices": null, "id": "cs_0346", "kind": "concept", "lang": "en", "question": "What is interprocess communication?", "steps": ["Processes isolated.", "Need channels.", "Pipes or sockets."], "subject": "computer_science", "text": "Answer: Data exchange channels.\nSteps:\n1. Processes isolated.\n2. Need channels.\n3. Pipes or sockets.", "topic": "operating_systems"}
{"answer": "2 items plus 3 gives 5.", "choices": null, "id": "cs_0347", "kind": "worked_example", "lang": "en", "question": "Cart has 2 items, add 3. How many items?", "steps": ["Start 2.", "Add 3.", "Total = 5."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. Start 2.\n2. Add 3.\n3. Total = 5.", "topic": "oop"}
{"answer": "Hash lookup averages O(1).", "choices": {"A": "Hash lookup", "B": "Binary search", "C": "Bubble sort", "D": "Merge sort"}, "id": "cs_0348", "kind": "multiple_choice", "lang": "en", "question": "Which averages O(1)?", "steps": ["Direct hashing.", "Constant average.", "Select option A."], "subject": "computer_science", "text": "Answer: Hash lookup.\nSteps:\n1. Direct hashing.\n2. Constant average.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "A reduction transforms one problem into another to compare hardness.", "choices": null, "id": "cs_0349", "kind": "concept", "lang": "en", "question": "What is a reduction?", "steps": ["Map instances.", "Preserve answers.", "Prove hardness."], "subject": "computer_science", "text": "Answer: Problem transformation.\nSteps:\n1. Map instances.\n2. Preserve answers.\n3. Prove hardness.", "topic": "complexity"}
{"answer": "Maximum je v kořenu, tedy 10.", "choices": null, "id": "cs_0350", "kind": "worked_example", "lang": "cs", "question": "Max-halda je [10,8,9]. Kde je maximum?", "steps": ["Kořen je 10.", "Děti menší.", "Maximum je 10."], "subject": "computer_science", "text": "Answer: 10.\nSteps:\n1. Kořen je 10.\n2. Děti menší.\n3. Maximum je 10.", "topic": "data_structures"}
{"answer": "A virtual environment isolates project packages from system Python.", "choices": null, "id": "cs_0351", "kind": "concept", "lang": "en", "question": "What is a Python virtual environment?", "steps": ["Separate folder.", "Own packages.", "Avoid conflicts."], "subject": "computer_science", "text": "Answer: Isolated packages.\nSteps:\n1. Separate folder.\n2. Own packages.\n3. Avoid conflicts.", "topic": "python"}
{"answer": "[5,6].indexOf(6) is 1.", "choices": {"A": "0", "B": "1", "C": "2", "D": "-1"}, "id": "cs_0352", "kind": "multiple_choice", "lang": "en", "question": "What does [5,6].indexOf(6) give?", "steps": ["Index from 0.", "6 at position 1.", "Select option B."], "subject": "computer_science", "text": "Answer: 1.\nSteps:\n1. Index from 0.\n2. 6 at position 1.\n3. Select option B.\nAnswer: (B)", "topic": "javascript"}
{"answer": "SELECT 12 + 30 returns 42.", "choices": null, "id": "cs_0353", "kind": "worked_example", "lang": "en", "question": "What does SELECT 12 + 30 return?", "steps": ["Add numbers.", "12 + 30 = 42.", "Result is 42."], "subject": "computer_science", "text": "Answer: 42.\nSteps:\n1. Add numbers.\n2. 12 + 30 = 42.\n3. Result is 42.", "topic": "sql"}
{"answer": "A /21 network has 2046 usable hosts.", "choices": null, "id": "cs_0354", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in a /21 network?", "steps": ["Host bits = 11.", "Addresses = 2048.", "Usable = 2048 - 2 = 2046."], "subject": "computer_science", "text": "Answer: 2046.\nSteps:\n1. Host bits = 11.\n2. Addresses = 2048.\n3. Usable = 2048 - 2 = 2046.", "topic": "networking"}
{"answer": "Normalizace odstraňuje redundanci rozdělením tabulek.", "choices": {"A": "Odstraňuje redundanci", "B": "Maže tabulky", "C": "Třídí řádky", "D": "Spojuje databáze"}, "id": "cs_0355", "kind": "multiple_choice", "lang": "cs", "question": "Co je normalizace databáze?", "steps": ["Méně duplicit.", "Více tabulek.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Odstraňuje redundanci.\nSteps:\n1. Méně duplicit.\n2. Více tabulek.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "The kernel is the core managing CPU, memory, and devices.", "choices": null, "id": "cs_0356", "kind": "concept", "lang": "en", "question": "What is an OS kernel?", "steps": ["Core software.", "Manages resources.", "Runs privileged."], "subject": "computer_science", "text": "Answer: Resource core.\nSteps:\n1. Core software.\n2. Manages resources.\n3. Runs privileged.", "topic": "operating_systems"}
{"answer": "20 plus 5 gives 25.", "choices": null, "id": "cs_0357", "kind": "worked_example", "lang": "en", "question": "Thermostat 20 degrees, increase(5). What is the setting?", "steps": ["Start 20.", "Add 5.", "Setting = 25."], "subject": "computer_science", "text": "Answer: 25.\nSteps:\n1. Start 20.\n2. Add 5.\n3. Setting = 25.", "topic": "oop"}
{"answer": "Floyd-Warshall computes all-pairs shortest paths.", "choices": {"A": "Dijkstra", "B": "Floyd-Warshall", "C": "Bubble sort", "D": "DFS"}, "id": "cs_0358", "kind": "multiple_choice", "lang": "en", "question": "Which computes all-pairs shortest paths?", "steps": ["All pairs needed.", "Floyd-Warshall does.", "Select option B."], "subject": "computer_science", "text": "Answer: Floyd-Warshall.\nSteps:\n1. All pairs needed.\n2. Floyd-Warshall does.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "Insertion sort worst case is O(n^2) with reverse-sorted input.", "choices": null, "id": "cs_0359", "kind": "concept", "lang": "en", "question": "What is insertion sort worst-case complexity?", "steps": ["Shift many items.", "Nested work.", "O(n^2)."], "subject": "computer_science", "text": "Answer: O(n^2).\nSteps:\n1. Shift many items.\n2. Nested work.\n3. O(n^2).", "topic": "complexity"}
{"answer": "Prostřední prvek je 3.", "choices": null, "id": "cs_0360", "kind": "worked_example", "lang": "cs", "question": "Seznam je [1,2,3,4,5]. Co je prostřední prvek?", "steps": ["Délka 5.", "Index 2.", "Prvek je 3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Délka 5.\n2. Index 2.\n3. Prvek je 3.", "topic": "data_structures"}
{"answer": "Docstrings are triple-quoted strings documenting modules and functions.", "choices": null, "id": "cs_0361", "kind": "concept", "lang": "en", "question": "What are Python docstrings?", "steps": ["Triple quotes.", "Describe purpose.", "Shown by help()."], "subject": "computer_science", "text": "Answer: Inline documentation.\nSteps:\n1. Triple quotes.\n2. Describe purpose.\n3. Shown by help().", "topic": "python"}
{"answer": "'hello'.slice(1,3) is 'el'.", "choices": {"A": "'el'", "B": "'hel'", "C": "'llo'", "D": "'h'"}, "id": "cs_0362", "kind": "multiple_choice", "lang": "en", "question": "What does 'hello'.slice(1,3) give?", "steps": ["Index 1 to 3.", "Letters e, l.", "Select option A."], "subject": "computer_science", "text": "Answer: 'el'.\nSteps:\n1. Index 1 to 3.\n2. Letters e, l.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "SELECT 2 * 3 * 4 returns 24.", "choices": null, "id": "cs_0363", "kind": "worked_example", "lang": "en", "question": "What does SELECT 2 * 3 * 4 return?", "steps": ["2 x 3 = 6.", "6 x 4 = 24.", "Result is 24."], "subject": "computer_science", "text": "Answer: 24.\nSteps:\n1. 2 x 3 = 6.\n2. 6 x 4 = 24.\n3. Result is 24.", "topic": "sql"}
{"answer": "100 MB at 10 MB/s takes 10 seconds.", "choices": null, "id": "cs_0364", "kind": "worked_example", "lang": "en", "question": "Download 100 MB at 10 MB/s. How many seconds?", "steps": ["Size 100.", "Rate 10.", "100 / 10 = 10."], "subject": "computer_science", "text": "Answer: 10.\nSteps:\n1. Size 100.\n2. Rate 10.\n3. 100 / 10 = 10.", "topic": "networking"}
{"answer": "LIMIT omezuje počet vrácených řádků.", "choices": {"A": "Omezuje počet", "B": "Třídí řádky", "C": "Spojuje tabulky", "D": "Maže řádky"}, "id": "cs_0365", "kind": "multiple_choice", "lang": "cs", "question": "Co dělá LIMIT?", "steps": ["Ber prvních N.", "Méně řádků.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: Omezuje počet.\nSteps:\n1. Ber prvních N.\n2. Méně řádků.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "A daemon is a background service process without direct user control.", "choices": null, "id": "cs_0366", "kind": "concept", "lang": "en", "question": "What is a system daemon?", "steps": ["Runs background.", "No terminal.", "Serves requests."], "subject": "computer_science", "text": "Answer: Background service.\nSteps:\n1. Runs background.\n2. No terminal.\n3. Serves requests.", "topic": "operating_systems"}
{"answer": "150 minus 150 leaves 0.", "choices": null, "id": "cs_0367", "kind": "worked_example", "lang": "en", "question": "Balance 150, withdraw(150). What is the balance?", "steps": ["Start 150.", "Minus 150.", "Balance = 0."], "subject": "computer_science", "text": "Answer: 0.\nSteps:\n1. Start 150.\n2. Minus 150.\n3. Balance = 0.", "topic": "oop"}
{"answer": "N-queens is solved with backtracking search.", "choices": {"A": "N-queens", "B": "Bubble sort", "C": "Linear search", "D": "BFS"}, "id": "cs_0368", "kind": "multiple_choice", "lang": "en", "question": "Which uses backtracking?", "steps": ["Try and undo.", "N-queens fits.", "Select option A."], "subject": "computer_science", "text": "Answer: N-queens.\nSteps:\n1. Try and undo.\n2. N-queens fits.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "Exponential growth eventually outgrows any polynomial bound.", "choices": null, "id": "cs_0369", "kind": "concept", "lang": "en", "question": "How do exponential and polynomial compare?", "steps": ["Polynomial bounded power.", "Exponential multiplies.", "Exponential wins."], "subject": "computer_science", "text": "Answer: Exponential outgrows.\nSteps:\n1. Polynomial bounded power.\n2. Exponential multiplies.\n3. Exponential wins.", "topic": "complexity"}
{"answer": "Plný strom hloubky 2 má 7 uzlů.", "choices": null, "id": "cs_0370", "kind": "worked_example", "lang": "cs", "question": "Kolik uzlů má plný binární strom hloubky 2?", "steps": ["Úroveň 0: 1.", "Úroveň 1: 2, úroveň 2: 4.", "Celkem 1+2+4 = 7."], "subject": "computer_science", "text": "Answer: 7.\nSteps:\n1. Úroveň 0: 1.\n2. Úroveň 1: 2, úroveň 2: 4.\n3. Celkem 1+2+4 = 7.", "topic": "data_structures"}
{"answer": "len() on a dict returns the number of keys.", "choices": null, "id": "cs_0371", "kind": "concept", "lang": "en", "question": "What does len() give for dicts?", "steps": ["Count keys.", "Each once.", "Example: 3 keys = 3."], "subject": "computer_science", "text": "Answer: Number of keys.\nSteps:\n1. Count keys.\n2. Each once.\n3. Example: 3 keys = 3.", "topic": "python"}
{"answer": "Array.isArray([]) is true.", "choices": {"A": "true", "B": "false", "C": "[]", "D": "TypeError"}, "id": "cs_0372", "kind": "multiple_choice", "lang": "en", "question": "What does Array.isArray([]) give?", "steps": ["[] is array.", "Check true.", "Select option A."], "subject": "computer_science", "text": "Answer: true.\nSteps:\n1. [] is array.\n2. Check true.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "SELECT 100 / 10 returns 10.", "choices": null, "id": "cs_0373", "kind": "worked_example", "lang": "en", "question": "What does SELECT 100 / 10 return?", "steps": ["Divide 100 by 10.", "100 / 10 = 10.", "Result is 10."], "subject": "computer_science", "text": "Answer: 10.\nSteps:\n1. Divide 100 by 10.\n2. 100 / 10 = 10.\n3. Result is 10.", "topic": "sql"}
{"answer": "Splitting /24 into /26 gives 4 subnets.", "choices": null, "id": "cs_0374", "kind": "worked_example", "lang": "en", "question": "Split /24 into /26. How many subnets?", "steps": ["Bits added = 2.", "2^2 = 4.", "Subnets = 4."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Bits added = 2.\n2. 2^2 = 4.\n3. Subnets = 4.", "topic": "networking"}
{"answer": "Tabulku maže příkaz DROP.", "choices": {"A": "DROP", "B": "DELETE", "C": "REMOVE", "D": "CLEAR"}, "id": "cs_0375", "kind": "multiple_choice", "lang": "cs", "question": "Která operace maže celou tabulku?", "steps": ["DELETE maže řádky.", "DROP maže tabulku.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: DROP.\nSteps:\n1. DELETE maže řádky.\n2. DROP maže tabulku.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "databases"}
{"answer": "Kontextový manažer řídí zdroje blokem with.", "choices": null, "id": "cs_0376", "kind": "concept", "lang": "cs", "question": "Co je kontextový manažer?", "steps": ["Blok with.", "Enter a exit.", "Příklad: open()."], "subject": "computer_science", "text": "Answer: Správa zdrojů.\nSteps:\n1. Blok with.\n2. Enter a exit.\n3. Příklad: open().", "topic": "python"}
{"answer": "Hoisting moves declarations to the top before execution.", "choices": null, "id": "cs_0377", "kind": "concept", "lang": "en", "question": "What is hoisting?", "steps": ["var hoisted.", "let in TDZ.", "Functions hoisted."], "subject": "computer_science", "text": "Answer: Top declarations.\nSteps:\n1. var hoisted.\n2. let in TDZ.\n3. Functions hoisted.", "topic": "javascript"}
{"answer": "SELECT returns 15.", "choices": {"A": "14", "B": "15", "C": "16", "D": "17"}, "id": "cs_0378", "kind": "multiple_choice", "lang": "en", "question": "Which value does SELECT 21 - 6 return?", "steps": ["Subtract.", "21-6=15.", "Select option B."], "subject": "computer_science", "text": "Answer: 15.\nSteps:\n1. Subtract.\n2. 21-6=15.\n3. Select option B.\nAnswer: (B)", "topic": "sql"}
{"answer": "TCP opens with SYN, SYN-ACK, and ACK before data.", "choices": null, "id": "cs_0379", "kind": "concept", "lang": "en", "question": "What is a TCP handshake?", "steps": ["SYN sent.", "SYN-ACK back.", "ACK confirms."], "subject": "computer_science", "text": "Answer: Three-way open.\nSteps:\n1. SYN sent.\n2. SYN-ACK back.\n3. ACK confirms.", "topic": "networking"}
{"answer": "Denormalization adds redundancy to speed up reads.", "choices": null, "id": "cs_0380", "kind": "concept", "lang": "en", "question": "What is denormalization?", "steps": ["Join less.", "Store twice.", "Faster reads."], "subject": "computer_science", "text": "Answer: Redundant speed.\nSteps:\n1. Join less.\n2. Store twice.\n3. Faster reads.", "topic": "databases"}
{"answer": "A microkernel keeps minimal core with services in user space.", "choices": null, "id": "cs_0381", "kind": "concept", "lang": "en", "question": "What is a microkernel?", "steps": ["IPC services.", "More stable.", "More switches."], "subject": "computer_science", "text": "Answer: Tiny core.\nSteps:\n1. IPC services.\n2. More stable.\n3. More switches.", "topic": "operating_systems"}
{"answer": "Composition holds parts while inheritance extends a parent type.", "choices": null, "id": "cs_0382", "kind": "concept", "lang": "en", "question": "What is composition versus inheritance?", "steps": ["Compose objects.", "Inherit behavior.", "Prefer compose."], "subject": "computer_science", "text": "Answer: Has versus is.\nSteps:\n1. Compose objects.\n2. Inherit behavior.\n3. Prefer compose.", "topic": "oop"}
{"answer": "Sorted = [2, 3, 4].", "choices": null, "id": "cs_0383", "kind": "worked_example", "lang": "en", "question": "Selection-sort [4, 2, 3] (case 1). Result?", "steps": ["Min 2.", "Swap.", "[2, 3, 4]."], "subject": "computer_science", "text": "Answer: [2, 3, 4].\nSteps:\n1. Min 2.\n2. Swap.\n3. [2, 3, 4].", "topic": "algorithms"}
{"answer": "Count = 4096.", "choices": null, "id": "cs_0384", "kind": "worked_example", "lang": "en", "question": "Subsets of 12 items (case 1). Count?", "steps": ["2^12.", "=4096.", "4096."], "subject": "computer_science", "text": "Answer: 4096.\nSteps:\n1. 2^12.\n2. =4096.\n3. 4096.", "topic": "complexity"}
{"answer": "A circular queue wraps indices to reuse freed slots.", "choices": null, "id": "cs_0385", "kind": "concept", "lang": "en", "question": "What is a circular queue?", "steps": ["Head tail.", "Modulo move.", "Fixed size."], "subject": "computer_science", "text": "Answer: Wrapped buffer.\nSteps:\n1. Head tail.\n2. Modulo move.\n3. Fixed size.", "topic": "data_structures"}
{"answer": "Context managers handle setup and cleanup with with blocks.", "choices": null, "id": "cs_0386", "kind": "concept", "lang": "en", "question": "What is a context manager?", "steps": ["Uses with.", "Calls enter/exit.", "Example: open()."], "subject": "computer_science", "text": "Answer: Setup and cleanup.\nSteps:\n1. Uses with.\n2. Calls enter/exit.\n3. Example: open().", "topic": "python"}
{"answer": "'x' + 4 is 'x4'.", "choices": {"A": "'4x'", "B": "'x4'", "C": "'5'", "D": "4"}, "id": "cs_0387", "kind": "multiple_choice", "lang": "en", "question": "What does 'x' + 4 give?", "steps": ["String concat.", "Result 'x4'.", "Select option B."], "subject": "computer_science", "text": "Answer: 'x4'.\nSteps:\n1. String concat.\n2. Result 'x4'.\n3. Select option B.\nAnswer: (B)", "topic": "javascript"}
{"answer": "SELECT returns 25.", "choices": {"A": "24", "B": "26", "C": "25", "D": "10"}, "id": "cs_0388", "kind": "multiple_choice", "lang": "cs", "question": "Kterou hodnotu vrátí SELECT 5 * 5?", "steps": ["Multiply.", "5x5=25.", "Select option C."], "subject": "computer_science", "text": "Answer: 25.\nSteps:\n1. Multiply.\n2. 5x5=25.\n3. Select option C.\nAnswer: (C)", "topic": "sql"}
{"answer": "Subnets = 4.", "choices": null, "id": "cs_0389", "kind": "worked_example", "lang": "en", "question": "Split /20 into /22 (case 1). How many subnets?", "steps": ["Bits 2.", "2^2=4.", "4."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Bits 2.\n2. 2^2=4.\n3. 4.", "topic": "networking"}
{"answer": "INSERT adds rows.", "choices": {"A": "SELECT", "B": "INSERT", "C": "DELETE", "D": "UPDATE"}, "id": "cs_0390", "kind": "multiple_choice", "lang": "en", "question": "Which adds rows (case 1)?", "steps": ["Write op.", "INSERT fits.", "Select option B."], "subject": "computer_science", "text": "Answer: INSERT.\nSteps:\n1. Write op.\n2. INSERT fits.\n3. Select option B.\nAnswer: (B)", "topic": "databases"}
{"answer": "Round-robin používá časová kvanta.", "choices": {"A": "FIFO", "B": "Round-robin", "C": "LIFO", "D": "Stack"}, "id": "cs_0391", "kind": "multiple_choice", "lang": "cs", "question": "Co používá kvanta (případ 1)?", "steps": ["Rotate tasks.", "Fixed quantum.", "Select option B."], "subject": "computer_science", "text": "Answer: Round-robin.\nSteps:\n1. Střídej úlohy.\n2. Pevné kvantum.\n3. Select option B.\nAnswer: (B)", "topic": "operating_systems"}
{"answer": "__init__ constructs.", "choices": {"A": "__len__", "B": "__init__", "C": "__add__", "D": "__str__"}, "id": "cs_0392", "kind": "multiple_choice", "lang": "cs", "question": "Co je konstruktor (případ 1)?", "steps": ["Init runs.", "Sets fields.", "Select option B."], "subject": "computer_science", "text": "Answer: __init__.\nSteps:\n1. Init runs.\n2. Sets fields.\n3. Select option B.\nAnswer: (B)", "topic": "oop"}
{"answer": "factorial(6) is 720.", "choices": {"A": "120", "B": "720", "C": "820", "D": "60"}, "id": "cs_0393", "kind": "multiple_choice", "lang": "en", "question": "What is factorial(6)?", "steps": ["Multiply down.", "Result 720.", "Select option B."], "subject": "computer_science", "text": "Answer: 720.\nSteps:\n1. Multiply down.\n2. Result 720.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "About 11.", "choices": null, "id": "cs_0394", "kind": "worked_example", "lang": "en", "question": "Binary steps n=2000 (case 2). About?", "steps": ["log2.", "~11.", "11."], "subject": "computer_science", "text": "Answer: 11.\nSteps:\n1. log2.\n2. ~11.\n3. 11.", "topic": "complexity"}
{"answer": "Load = 0.83.", "choices": null, "id": "cs_0395", "kind": "worked_example", "lang": "en", "question": "10 items in 12 slots (case 1). Load?", "steps": ["10/12.", "=0.83.", "0.83."], "subject": "computer_science", "text": "Answer: 0.83.\nSteps:\n1. 10/12.\n2. =0.83.\n3. 0.83.", "topic": "data_structures"}
{"answer": "11//4 is 2.", "choices": {"A": "3", "B": "2", "C": "1", "D": "4"}, "id": "cs_0396", "kind": "multiple_choice", "lang": "en", "question": "What does 11 // 4 give in Python?", "steps": ["Floor divide.", "11//4=2.", "Select option B."], "subject": "computer_science", "text": "Answer: 2.\nSteps:\n1. Floor divide.\n2. 11//4=2.\n3. Select option B.\nAnswer: (B)", "topic": "python"}
{"answer": "Result is 'hi1'.", "choices": null, "id": "cs_0397", "kind": "worked_example", "lang": "en", "question": "What does 'Hi1'.toLowerCase() give?", "steps": ["Lowercase.", "'hi1'.", "Result."], "subject": "computer_science", "text": "Answer: 'hi1'.\nSteps:\n1. Lowercase.\n2. 'hi1'.\n3. Result.", "topic": "javascript"}
{"answer": "SELECT returns 11.", "choices": null, "id": "cs_0398", "kind": "worked_example", "lang": "en", "question": "What does SELECT 22 / 2 return?", "steps": ["Divide.", "22/2=11.", "11."], "subject": "computer_science", "text": "Answer: 11.\nSteps:\n1. Divide.\n2. 22/2=11.\n3. 11.", "topic": "sql"}
{"answer": "192.168.1.1 is private.", "choices": {"A": "8.8.1.1", "B": "192.168.1.1", "C": "1.1.1.1", "D": "203.0.1.1"}, "id": "cs_0399", "kind": "multiple_choice", "lang": "en", "question": "Which IP is private (set 1)?", "steps": ["Private ranges.", "192.168.1.1 fits.", "Select option B."], "subject": "computer_science", "text": "Answer: 192.168.1.1.\nSteps:\n1. Private ranges.\n2. 192.168.1.1 fits.\n3. Select option B.\nAnswer: (B)", "topic": "networking"}
{"answer": "Sharding splits data across servers by key ranges.", "choices": null, "id": "cs_0400", "kind": "concept", "lang": "en", "question": "What is sharding?", "steps": ["Hash key.", "Route shard.", "Scale out."], "subject": "computer_science", "text": "Answer: Split by key.\nSteps:\n1. Hash key.\n2. Route shard.\n3. Scale out.", "topic": "databases"}
{"answer": "Mutex ensures one.", "choices": {"A": "Queue", "B": "Array", "C": "Mutex", "D": "File"}, "id": "cs_0401", "kind": "multiple_choice", "lang": "en", "question": "What ensures one access (case 2)?", "steps": ["Lock it.", "One holder.", "Select option C."], "subject": "computer_science", "text": "Answer: Mutex.\nSteps:\n1. Lock it.\n2. One holder.\n3. Select option C.\nAnswer: (C)", "topic": "operating_systems"}
{"answer": "Encapsulation bundles.", "choices": {"A": "Loop", "B": "Sort", "C": "Encapsulation", "D": "Search"}, "id": "cs_0402", "kind": "multiple_choice", "lang": "en", "question": "Which bundles data and methods (case 2)?", "steps": ["Hide inside.", "One unit.", "Select option C."], "subject": "computer_science", "text": "Answer: Encapsulation.\nSteps:\n1. Hide inside.\n2. One unit.\n3. Select option C.\nAnswer: (C)", "topic": "oop"}
{"answer": "Steps = 7.", "choices": {"A": "6", "B": "8", "C": "7", "D": "128"}, "id": "cs_0403", "kind": "multiple_choice", "lang": "cs", "question": "Kolik kroků binárně pro n = 128?", "steps": ["log2(128)=7.", "Halve 7x.", "Select option C."], "subject": "computer_science", "text": "Answer: 7.\nSteps:\n1. log2(128)=7.\n2. Halve 7x.\n3. Select option C.\nAnswer: (C)", "topic": "algorithms"}
{"answer": "Iterations = 27.", "choices": {"A": "9", "B": "27", "C": "18", "D": "12"}, "id": "cs_0404", "kind": "multiple_choice", "lang": "en", "question": "Triple loops n = 3. How many iterations?", "steps": ["3^3.", "=27.", "Select option B."], "subject": "computer_science", "text": "Answer: 27.\nSteps:\n1. 3^3.\n2. =27.\n3. Select option B.\nAnswer: (B)", "topic": "complexity"}
{"answer": "K7 has 21 edges.", "choices": {"A": "20", "B": "21", "C": "22", "D": "49"}, "id": "cs_0405", "kind": "multiple_choice", "lang": "en", "question": "How many edges in K7?", "steps": ["n(n-1)/2.", "=21.", "Select option B."], "subject": "computer_science", "text": "Answer: 21.\nSteps:\n1. n(n-1)/2.\n2. =21.\n3. Select option B.\nAnswer: (B)", "topic": "data_structures"}
{"answer": "Asyncio runs concurrent I/O with async and await.", "choices": null, "id": "cs_0406", "kind": "concept", "lang": "en", "question": "What is asyncio used for?", "steps": ["Async def.", "Await pauses.", "Event loop runs."], "subject": "computer_science", "text": "Answer: Concurrent I/O.\nSteps:\n1. Async def.\n2. Await pauses.\n3. Event loop runs.", "topic": "python"}
{"answer": "Repeat gives 'abababab'.", "choices": null, "id": "cs_0407", "kind": "worked_example", "lang": "en", "question": "What does 'ab'.repeat(4) give?", "steps": ["Repeat.", "4x.", "'abababab'."], "subject": "computer_science", "text": "Answer: 'abababab'.\nSteps:\n1. Repeat.\n2. 4x.\n3. 'abababab'.", "topic": "javascript"}
{"answer": "MAX is 8.", "choices": {"A": "6", "B": "7", "C": "9", "D": "8"}, "id": "cs_0408", "kind": "multiple_choice", "lang": "en", "question": "Which value does SELECT MAX of (6,8,7) give?", "steps": ["Compare.", "Largest 8.", "Select option D."], "subject": "computer_science", "text": "Answer: 8.\nSteps:\n1. Compare.\n2. Largest 8.\n3. Select option D.\nAnswer: (D)", "topic": "sql"}
{"answer": "UDP suits low-latency loss-tolerant traffic like calls.", "choices": null, "id": "cs_0409", "kind": "concept", "lang": "en", "question": "What is UDP used for?", "steps": ["No handshake.", "No retry.", "Low overhead."], "subject": "computer_science", "text": "Answer: Fast datagrams.\nSteps:\n1. No handshake.\n2. No retry.\n3. Low overhead.", "topic": "networking"}
{"answer": "Max = 12.", "choices": null, "id": "cs_0410", "kind": "worked_example", "lang": "en", "question": "Cross-join 3 and 4 rows (case 1). Max?", "steps": ["3x4.", "=12.", "12."], "subject": "computer_science", "text": "Answer: 12.\nSteps:\n1. 3x4.\n2. =12.\n3. 12.", "topic": "databases"}
{"answer": "Kernel manages.", "choices": {"A": "Shell", "B": "App", "C": "Driver", "D": "Kernel"}, "id": "cs_0411", "kind": "multiple_choice", "lang": "cs", "question": "Co řídí zdroje (případ 3)?", "steps": ["Core role.", "CPU mem.", "Select option D."], "subject": "computer_science", "text": "Answer: Kernel.\nSteps:\n1. Core role.\n2. CPU mem.\n3. Select option D.\nAnswer: (D)", "topic": "operating_systems"}
{"answer": "Area = 20.", "choices": null, "id": "cs_0412", "kind": "worked_example", "lang": "en", "question": "Rectangle 4 by 5 (case 1). Area?", "steps": ["4x5.", "=20.", "20."], "subject": "computer_science", "text": "Answer: 20.\nSteps:\n1. 4x5.\n2. =20.\n3. 20.", "topic": "oop"}
{"answer": "Backtracking tries options and undoes failing paths.", "choices": null, "id": "cs_0413", "kind": "concept", "lang": "en", "question": "What is backtracking?", "steps": ["Choose step.", "Recurse on.", "Undo if fail."], "subject": "computer_science", "text": "Answer: Try and undo.\nSteps:\n1. Choose step.\n2. Recurse on.\n3. Undo if fail.", "topic": "algorithms"}
{"answer": "Pseudo-polynomial depends on numeric values, not just input length.", "choices": null, "id": "cs_0414", "kind": "concept", "lang": "en", "question": "What is pseudo-polynomial time?", "steps": ["Knapsack case.", "Big numbers slow.", "Not true poly."], "subject": "computer_science", "text": "Answer: Value dependent.\nSteps:\n1. Knapsack case.\n2. Big numbers slow.\n3. Not true poly.", "topic": "complexity"}
{"answer": "Edges = 45.", "choices": null, "id": "cs_0415", "kind": "worked_example", "lang": "en", "question": "Edges in K10 (case 2). Count?", "steps": ["n(n-1)/2.", "=45.", "45."], "subject": "computer_science", "text": "Answer: 45.\nSteps:\n1. n(n-1)/2.\n2. =45.\n3. 45.", "topic": "data_structures"}
{"answer": "max is 4.", "choices": null, "id": "cs_0416", "kind": "worked_example", "lang": "en", "question": "What does max([1,4,2]) return?", "steps": ["Compare three.", "Largest 4.", "Result 4."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Compare three.\n2. Largest 4.\n3. Result 4.", "topic": "python"}
{"answer": "The event loop runs queued callbacks when the stack is empty.", "choices": null, "id": "cs_0417", "kind": "concept", "lang": "en", "question": "What is the event loop?", "steps": ["Stack first.", "Queue next.", "Async appears."], "subject": "computer_science", "text": "Answer: Queued callbacks.\nSteps:\n1. Stack first.\n2. Queue next.\n3. Async appears.", "topic": "javascript"}
{"answer": "Result is 0.", "choices": null, "id": "cs_0418", "kind": "worked_example", "lang": "en", "question": "Compute SELECT 12 % 3.", "steps": ["Modulo.", "12%3=0.", "0."], "subject": "computer_science", "text": "Answer: 0.\nSteps:\n1. Modulo.\n2. 12%3=0.\n3. 0.", "topic": "sql"}
{"answer": "UDP is connectionless.", "choices": {"A": "TCP", "B": "HTTP", "C": "UDP", "D": "IP"}, "id": "cs_0419", "kind": "multiple_choice", "lang": "en", "question": "What is connectionless (case 2)?", "steps": ["No handshake.", "UDP fits.", "Select option C."], "subject": "computer_science", "text": "Answer: UDP.\nSteps:\n1. No handshake.\n2. UDP fits.\n3. Select option C.\nAnswer: (C)", "topic": "networking"}
{"answer": "Count = 7.", "choices": null, "id": "cs_0420", "kind": "worked_example", "lang": "en", "question": "INSERT 7 rows into empty (case 2). Count?", "steps": ["Start 0.", "Add 7.", "7."], "subject": "computer_science", "text": "Answer: 7.\nSteps:\n1. Start 0.\n2. Add 7.\n3. 7.", "topic": "databases"}
{"answer": "FIFO evicts oldest.", "choices": {"A": "FIFO", "B": "LIFO", "C": "LRU", "D": "Random"}, "id": "cs_0421", "kind": "multiple_choice", "lang": "en", "question": "Which evicts oldest page (case 4)?", "steps": ["Queue order.", "Oldest first.", "Select option A."], "subject": "computer_science", "text": "Answer: FIFO.\nSteps:\n1. Queue order.\n2. Oldest first.\n3. Select option A.\nAnswer: (A)", "topic": "operating_systems"}
{"answer": "Inheritance reuses.", "choices": {"A": "Loop", "B": "Recursion", "C": "Sorting", "D": "Inheritance"}, "id": "cs_0422", "kind": "multiple_choice", "lang": "en", "question": "Which reuses parent behavior (case 3)?", "steps": ["Child extends.", "Gets methods.", "Select option D."], "subject": "computer_science", "text": "Answer: Inheritance.\nSteps:\n1. Child extends.\n2. Gets methods.\n3. Select option D.\nAnswer: (D)", "topic": "oop"}
{"answer": "factorial(8) = 40320.", "choices": null, "id": "cs_0423", "kind": "worked_example", "lang": "en", "question": "Compute factorial(8) (case 2).", "steps": ["Expand.", "Product.", "40320."], "subject": "computer_science", "text": "Answer: 40320.\nSteps:\n1. Expand.\n2. Product.\n3. 40320.", "topic": "algorithms"}
{"answer": "Master theorem solves divide-and-conquer recurrences quickly.", "choices": null, "id": "cs_0424", "kind": "concept", "lang": "en", "question": "What is the master theorem?", "steps": ["Compare parts.", "Pick case.", "Gives Big-O."], "subject": "computer_science", "text": "Answer: Recurrence solver.\nSteps:\n1. Compare parts.\n2. Pick case.\n3. Gives Big-O.", "topic": "complexity"}
{"answer": "A deque allows push and pop on both ends.", "choices": null, "id": "cs_0425", "kind": "concept", "lang": "en", "question": "What is a deque?", "steps": ["Left right.", "O(1) ends.", "Flexible."], "subject": "computer_science", "text": "Answer: Both ends.\nSteps:\n1. Left right.\n2. O(1) ends.\n3. Flexible.", "topic": "data_structures"}
{"answer": "x becomes [1, 2, 12].", "choices": null, "id": "cs_0426", "kind": "worked_example", "lang": "en", "question": "x=[1,2]; x.append(12). What is x?", "steps": ["Start [1,2].", "Append 12.", "x=[1, 2, 12]."], "subject": "computer_science", "text": "Answer: [1, 2, 12].\nSteps:\n1. Start [1,2].\n2. Append 12.\n3. x=[1, 2, 12].", "topic": "python"}
{"answer": "12%4 is 0.", "choices": {"A": "1", "B": "2", "C": "0", "D": "4"}, "id": "cs_0427", "kind": "multiple_choice", "lang": "en", "question": "What does 12 % 4 give in JavaScript?", "steps": ["Remainder.", "12%4=0.", "Select option C."], "subject": "computer_science", "text": "Answer: 0.\nSteps:\n1. Remainder.\n2. 12%4=0.\n3. Select option C.\nAnswer: (C)", "topic": "javascript"}
{"answer": "LENGTH is 6.", "choices": null, "id": "cs_0428", "kind": "worked_example", "lang": "en", "question": "Compute SELECT LENGTH('hello3').", "steps": ["Count chars.", "'hello3'.", "6."], "subject": "computer_science", "text": "Answer: 6.\nSteps:\n1. Count chars.\n2. 'hello3'.\n3. 6.", "topic": "sql"}
{"answer": "ARP maps IP to MAC.", "choices": {"A": "IP to port", "B": "MAC to IP", "C": "Port to MAC", "D": "IP to MAC"}, "id": "cs_0429", "kind": "multiple_choice", "lang": "en", "question": "What does ARP map (case 3)?", "steps": ["LAN lookup.", "IP to MAC.", "Select option D."], "subject": "computer_science", "text": "Answer: IP to MAC.\nSteps:\n1. LAN lookup.\n2. IP to MAC.\n3. Select option D.\nAnswer: (D)", "topic": "networking"}
{"answer": "Returned = 5.", "choices": null, "id": "cs_0430", "kind": "worked_example", "lang": "en", "question": "13 rows, WHERE matches 5 (case 3). Returned?", "steps": ["Total 13.", "Match 5.", "5."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. Total 13.\n2. Match 5.\n3. 5.", "topic": "databases"}
{"answer": "Copy-on-write shares pages until a write forces a copy.", "choices": null, "id": "cs_0431", "kind": "concept", "lang": "en", "question": "What is copy-on-write?", "steps": ["Fork shares.", "Write copies.", "Saves memory."], "subject": "computer_science", "text": "Answer: Share until write.\nSteps:\n1. Fork shares.\n2. Write copies.\n3. Saves memory.", "topic": "operating_systems"}
{"answer": "An abstract class cannot instantiate and defines required methods.", "choices": null, "id": "cs_0432", "kind": "concept", "lang": "en", "question": "What is an abstract class?", "steps": ["No direct make.", "Subclass fills.", "Enforces API."], "subject": "computer_science", "text": "Answer: Unfinished blueprint.\nSteps:\n1. No direct make.\n2. Subclass fills.\n3. Enforces API.", "topic": "oop"}
{"answer": "DP solves overlapping subproblems once and reuses answers.", "choices": null, "id": "cs_0433", "kind": "concept", "lang": "en", "question": "What is dynamic programming?", "steps": ["Memo table.", "Bottom up.", "Optimal parts."], "subject": "computer_science", "text": "Answer: Reuse subanswers.\nSteps:\n1. Memo table.\n2. Bottom up.\n3. Optimal parts.", "topic": "algorithms"}
{"answer": "200 vs 40000.", "choices": null, "id": "cs_0434", "kind": "worked_example", "lang": "en", "question": "O(n) vs O(n^2) n=200 (case 3). Steps?", "steps": ["O(n)=200.", "O(n^2)=40000.", "Done."], "subject": "computer_science", "text": "Answer: 200 vs 40000.\nSteps:\n1. O(n)=200.\n2. O(n^2)=40000.\n3. Done.", "topic": "complexity"}
{"answer": "A trie stores strings by shared prefixes for fast lookup.", "choices": null, "id": "cs_0435", "kind": "concept", "lang": "en", "question": "What is a trie?", "steps": ["Char nodes.", "Share start.", "Word end."], "subject": "computer_science", "text": "Answer: Prefix tree.\nSteps:\n1. Char nodes.\n2. Share start.\n3. Word end.", "topic": "data_structures"}
{"answer": "12%5 je 2.", "choices": {"A": "3", "B": "4", "C": "2", "D": "5"}, "id": "cs_0436", "kind": "multiple_choice", "lang": "cs", "question": "Co vrátí 12 % 5 v Pythonu?", "steps": ["Zbytek.", "12%5=2.", "Vyber možnost C."], "subject": "computer_science", "text": "Answer: 2.\nSteps:\n1. Zbytek.\n2. 12%5=2.\n3. Vyber možnost C.\nAnswer: (C)", "topic": "python"}
{"answer": "Math.floor(3.7) is 3.", "choices": null, "id": "cs_0437", "kind": "worked_example", "lang": "en", "question": "What does Math.floor(3.7) give?", "steps": ["Round down.", "3.7 to 3.", "3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Round down.\n2. 3.7 to 3.\n3. 3.", "topic": "javascript"}
{"answer": "MIN is 9.", "choices": null, "id": "cs_0438", "kind": "worked_example", "lang": "en", "question": "Compute SELECT MIN of (9,12).", "steps": ["Compare.", "Smallest 9.", "9."], "subject": "computer_science", "text": "Answer: 9.\nSteps:\n1. Compare.\n2. Smallest 9.\n3. 9.", "topic": "sql"}
{"answer": "Time = 3.5 s.", "choices": null, "id": "cs_0439", "kind": "worked_example", "lang": "en", "question": "Download 70 MB at 20 MB/s (case 2). Seconds?", "steps": ["Size 70.", "Rate 20.", "3.5 s."], "subject": "computer_science", "text": "Answer: 3.5.\nSteps:\n1. Size 70.\n2. Rate 20.\n3. 3.5 s.", "topic": "networking"}
{"answer": "Index speeds reads.", "choices": {"A": "Deletes data", "B": "Drops table", "C": "Speeds reads", "D": "Stops DB"}, "id": "cs_0440", "kind": "multiple_choice", "lang": "cs", "question": "K čemu je index (případ 2)?", "steps": ["Lookup aid.", "Faster.", "Select option C."], "subject": "computer_science", "text": "Answer: Speeds reads.\nSteps:\n1. Lookup aid.\n2. Faster.\n3. Select option C.\nAnswer: (C)", "topic": "databases"}
{"answer": "Thrashing is excess paging that stalls useful work.", "choices": null, "id": "cs_0441", "kind": "concept", "lang": "en", "question": "What is thrashing?", "steps": ["Too few frames.", "Swap always.", "Throughput falls."], "subject": "computer_science", "text": "Answer: Paging storm.\nSteps:\n1. Too few frames.\n2. Swap always.\n3. Throughput falls.", "topic": "operating_systems"}
{"answer": "Value = 8.", "choices": null, "id": "cs_0442", "kind": "worked_example", "lang": "en", "question": "Counter 7, inc() (case 2). Value?", "steps": ["Start 7.", "Plus 1.", "8."], "subject": "computer_science", "text": "Answer: 8.\nSteps:\n1. Start 7.\n2. Plus 1.\n3. 8.", "topic": "oop"}
{"answer": "A spanning tree connects all vertices with fewest edges.", "choices": null, "id": "cs_0443", "kind": "concept", "lang": "en", "question": "What is a spanning tree?", "steps": ["V-1 edges.", "No cycles.", "Min variant."], "subject": "computer_science", "text": "Answer: Connect all.\nSteps:\n1. V-1 edges.\n2. No cycles.\n3. Min variant.", "topic": "algorithms"}
{"answer": "Průměrná konstantní cena přes mnoho operací.", "choices": null, "id": "cs_0444", "kind": "concept", "lang": "cs", "question": "Co je amortizovaná složitost O(1)?", "steps": ["Občas drahá.", "Většinou levná.", "Pole."], "subject": "computer_science", "text": "Answer: Průměrná konstanta.\nSteps:\n1. Občas drahá.\n2. Většinou levná.\n3. Pole.", "topic": "complexity"}
{"answer": "Kruhová fronta obtáčí indexy.", "choices": null, "id": "cs_0445", "kind": "concept", "lang": "cs", "question": "Co je kruhová fronta?", "steps": ["Hlava pata.", "Modulo.", "Pevná velikost."], "subject": "computer_science", "text": "Answer: Obtočený buffer.\nSteps:\n1. Hlava pata.\n2. Modulo.\n3. Pevná velikost.", "topic": "data_structures"}
{"answer": "Result is [5, 6, 7].", "choices": null, "id": "cs_0446", "kind": "worked_example", "lang": "en", "question": "What does list(range(5,8)) give?", "steps": ["From 5.", "To 7.", "[5, 6, 7]."], "subject": "computer_science", "text": "Answer: [5, 6, 7].\nSteps:\n1. From 5.\n2. To 7.\n3. [5, 6, 7].", "topic": "python"}
{"answer": "4+9 is 13.", "choices": null, "id": "cs_0447", "kind": "worked_example", "lang": "en", "question": "What does 4 + 9 give in JavaScript?", "steps": ["Add.", "=13.", "13."], "subject": "computer_science", "text": "Answer: 13.\nSteps:\n1. Add.\n2. =13.\n3. 13.", "topic": "javascript"}
{"answer": "Poddotaz je SELECT vnořený v jiném dotazu.", "choices": null, "id": "cs_0448", "kind": "concept", "lang": "cs", "question": "Co je poddotaz?", "steps": ["Vnitřní běží.", "Vnější použije.", "Ve WHERE či FROM."], "subject": "computer_science", "text": "Answer: Vnořený SELECT.\nSteps:\n1. Vnitřní běží.\n2. Vnější použije.\n3. Ve WHERE či FROM.", "topic": "sql"}
{"answer": "TCP otevírá spojením SYN, SYN-ACK a ACK.", "choices": null, "id": "cs_0449", "kind": "concept", "lang": "cs", "question": "Co je TCP handshake?", "steps": ["SYN ven.", "SYN-ACK zpět.", "ACK potvrdí."], "subject": "computer_science", "text": "Answer: Trojcestné otevření.\nSteps:\n1. SYN ven.\n2. SYN-ACK zpět.\n3. ACK potvrdí.", "topic": "networking"}
{"answer": "Remain = 9.", "choices": null, "id": "cs_0450", "kind": "worked_example", "lang": "en", "question": "Table has 14 rows, DELETE removes 5 (case 4). Remain?", "steps": ["Start 14.", "Minus 5.", "9."], "subject": "computer_science", "text": "Answer: 9.\nSteps:\n1. Start 14.\n2. Minus 5.\n3. 9.", "topic": "databases"}
{"answer": "Stránky se načítají až při prvním přístupu.", "choices": null, "id": "cs_0451", "kind": "concept", "lang": "cs", "question": "Co je stránkování na žádost?", "steps": ["Start prázdný.", "Fault načte.", "Méně I/O."], "subject": "computer_science", "text": "Answer: Líné načtení.\nSteps:\n1. Start prázdný.\n2. Fault načte.\n3. Méně I/O.", "topic": "operating_systems"}
{"answer": "An interface lists required methods without implementation.", "choices": null, "id": "cs_0452", "kind": "concept", "lang": "en", "question": "What is an interface?", "steps": ["Contract only.", "Class fulfills.", "Many can share."], "subject": "computer_science", "text": "Answer: Required methods.\nSteps:\n1. Contract only.\n2. Class fulfills.\n3. Many can share.", "topic": "oop"}
{"answer": "In-place sorts use O(1) extra space by rearranging input.", "choices": null, "id": "cs_0453", "kind": "concept", "lang": "en", "question": "What is in-place sorting?", "steps": ["Swap inside.", "Save memory.", "Example: heap."], "subject": "computer_science", "text": "Answer: No extra array.\nSteps:\n1. Swap inside.\n2. Save memory.\n3. Example: heap.", "topic": "algorithms"}
{"answer": "Iterations = 400.", "choices": null, "id": "cs_0454", "kind": "worked_example", "lang": "en", "question": "Nested loops n=20 (case 4). Iterations?", "steps": ["20x20.", "=400.", "400."], "subject": "computer_science", "text": "Answer: 400.\nSteps:\n1. 20x20.\n2. =400.\n3. 400.", "topic": "complexity"}
{"answer": "Returns 8.", "choices": null, "id": "cs_0455", "kind": "worked_example", "lang": "en", "question": "Enqueue 8,9 then dequeue (case 3). Returns?", "steps": ["Front 8.", "FIFO.", "8."], "subject": "computer_science", "text": "Answer: 8.\nSteps:\n1. Front 8.\n2. FIFO.\n3. 8.", "topic": "data_structures"}
{"answer": "2**6 je 64.", "choices": {"A": "32", "B": "128", "C": "12", "D": "64"}, "id": "cs_0456", "kind": "multiple_choice", "lang": "cs", "question": "Co vrátí 2**6?", "steps": ["Mocnina dvou.", "2**6=64.", "Vyber možnost D."], "subject": "computer_science", "text": "Answer: 64.\nSteps:\n1. Mocnina dvou.\n2. 2**6=64.\n3. Vyber možnost D.\nAnswer: (D)", "topic": "python"}
{"answer": "Join gives '5-6-7'.", "choices": null, "id": "cs_0457", "kind": "worked_example", "lang": "en", "question": "What does [5,6,7].join('-') give?", "steps": ["Join dash.", "Parts.", "'5-6-7'."], "subject": "computer_science", "text": "Answer: '5-6-7'.\nSteps:\n1. Join dash.\n2. Parts.\n3. '5-6-7'.", "topic": "javascript"}
{"answer": "Sum is 45.", "choices": null, "id": "cs_0458", "kind": "worked_example", "lang": "en", "question": "Sum 1..9 via SELECT. What value?", "steps": ["n=9.", "n(n+1)/2.", "45."], "subject": "computer_science", "text": "Answer: 45.\nSteps:\n1. n=9.\n2. n(n+1)/2.\n3. 45.", "topic": "sql"}
{"answer": "TCP opens SYN, SYN-ACK, ACK.", "choices": {"A": "SYN, SYN-ACK, ACK", "B": "SYN, ACK", "C": "ACK, FIN", "D": "SYN, FIN"}, "id": "cs_0459", "kind": "multiple_choice", "lang": "en", "question": "What is TCP open order (case 4)?", "steps": ["Three steps.", "In order.", "Select option A."], "subject": "computer_science", "text": "Answer: SYN, SYN-ACK, ACK.\nSteps:\n1. Three steps.\n2. In order.\n3. Select option A.\nAnswer: (A)", "topic": "networking"}
{"answer": "Max = 8.", "choices": null, "id": "cs_0460", "kind": "worked_example", "lang": "en", "question": "Cross-join 2 and 4 rows (case 5). Max?", "steps": ["2x4.", "=8.", "8."], "subject": "computer_science", "text": "Answer: 8.\nSteps:\n1. 2x4.\n2. =8.\n3. 8.", "topic": "databases"}
{"answer": "Round-robin uses slices.", "choices": {"A": "FIFO", "B": "Round-robin", "C": "LIFO", "D": "Stack"}, "id": "cs_0461", "kind": "multiple_choice", "lang": "en", "question": "Which uses time slices (case 5)?", "steps": ["Rotate tasks.", "Fixed quantum.", "Select option B."], "subject": "computer_science", "text": "Answer: Round-robin.\nSteps:\n1. Rotate tasks.\n2. Fixed quantum.\n3. Select option B.\nAnswer: (B)", "topic": "operating_systems"}
{"answer": "B().x = 5.", "choices": null, "id": "cs_0462", "kind": "worked_example", "lang": "en", "question": "Class A x=5, B(A) (case 3). B().x?", "steps": ["A sets.", "B inherits.", "5."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. A sets.\n2. B inherits.\n3. 5.", "topic": "oop"}
{"answer": "Bubble sort swaps adjacent.", "choices": {"A": "Merge sort", "B": "Binary search", "C": "BFS", "D": "Bubble sort"}, "id": "cs_0463", "kind": "multiple_choice", "lang": "en", "question": "Which swaps adjacent out-of-order (case 3)?", "steps": ["Neighbor pairs.", "Swap if wrong.", "Select option D."], "subject": "computer_science", "text": "Answer: Bubble sort.\nSteps:\n1. Neighbor pairs.\n2. Swap if wrong.\n3. Select option D.\nAnswer: (D)", "topic": "algorithms"}
{"answer": "Count = 2048.", "choices": null, "id": "cs_0464", "kind": "worked_example", "lang": "en", "question": "Subsets of 11 items (case 5). Count?", "steps": ["2^11.", "=2048.", "2048."], "subject": "computer_science", "text": "Answer: 2048.\nSteps:\n1. 2^11.\n2. =2048.\n3. 2048.", "topic": "complexity"}
{"answer": "Open addressing probes other slots on collision.", "choices": null, "id": "cs_0465", "kind": "concept", "lang": "en", "question": "What is open addressing?", "steps": ["Hash spot.", "Linear probe.", "Fill gaps."], "subject": "computer_science", "text": "Answer: Probe slots.\nSteps:\n1. Hash spot.\n2. Linear probe.\n3. Fill gaps.", "topic": "data_structures"}
{"answer": "'ab'*3 is 'ababab'.", "choices": null, "id": "cs_0466", "kind": "worked_example", "lang": "en", "question": "What does 'ab'*3 give?", "steps": ["Repeat.", "3x.", "'ababab'."], "subject": "computer_science", "text": "Answer: 'ababab'.\nSteps:\n1. Repeat.\n2. 3x.\n3. 'ababab'.", "topic": "python"}
{"answer": "Math.ceil(3.2) je 4.", "choices": {"A": "3", "B": "5", "C": "2", "D": "4"}, "id": "cs_0467", "kind": "multiple_choice", "lang": "cs", "question": "Co vrátí Math.ceil(3.2)?", "steps": ["Round up.", "3.2 to 4.", "Select option D."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Zaokrouhli nahoru.\n2. 3,2 na 4.\n3. Select option D.\nAnswer: (D)", "topic": "javascript"}
{"answer": "LIKE hledá text podle vzoru s % a _.", "choices": null, "id": "cs_0468", "kind": "concept", "lang": "cs", "question": "Co je LIKE?", "steps": ["% sekvence.", "_ jeden znak.", "Pozor case."], "subject": "computer_science", "text": "Answer: Vzor textu.\nSteps:\n1. % sekvence.\n2. _ jeden znak.\n3. Pozor case.", "topic": "sql"}
{"answer": "Rate = 20.", "choices": null, "id": "cs_0469", "kind": "worked_example", "lang": "en", "question": "RTT 50 ms (case 3). Serial req/s?", "steps": ["1000 ms.", "1000/50=20.", "20."], "subject": "computer_science", "text": "Answer: 20.\nSteps:\n1. 1000 ms.\n2. 1000/50=20.\n3. 20.", "topic": "networking"}
{"answer": "Replication copies data to replicas for safety and reads.", "choices": null, "id": "cs_0470", "kind": "concept", "lang": "en", "question": "What is replication?", "steps": ["Primary writes.", "Replicas copy.", "Failover ready."], "subject": "computer_science", "text": "Answer: Copied data.\nSteps:\n1. Primary writes.\n2. Replicas copy.\n3. Failover ready.", "topic": "databases"}
{"answer": "Faults = 4.", "choices": null, "id": "cs_0471", "kind": "worked_example", "lang": "en", "question": "4 frames empty, refs 1..4 (case 1). Faults?", "steps": ["All miss.", "Count 4.", "4."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. All miss.\n2. Count 4.\n3. 4.", "topic": "operating_systems"}
{"answer": "super() calls parent.", "choices": {"A": "Calls parent", "B": "Creates child", "C": "Deletes obj", "D": "Copies list"}, "id": "cs_0472", "kind": "multiple_choice", "lang": "en", "question": "What does super() do (case 4)?", "steps": ["Parent link.", "Call method.", "Select option A."], "subject": "computer_science", "text": "Answer: Calls parent.\nSteps:\n1. Parent link.\n2. Call method.\n3. Select option A.\nAnswer: (A)", "topic": "oop"}
{"answer": "Moves = 31.", "choices": null, "id": "cs_0473", "kind": "worked_example", "lang": "en", "question": "Hanoi 5 disks (case 3). Moves?", "steps": ["2^5-1.", "=31.", "31."], "subject": "computer_science", "text": "Answer: 31.\nSteps:\n1. 2^5-1.\n2. =31.\n3. 31.", "topic": "algorithms"}
{"answer": "Graph search costs O(V+E) visiting nodes and edges once.", "choices": null, "id": "cs_0474", "kind": "concept", "lang": "en", "question": "What is Big-O of BFS and DFS?", "steps": ["Each node.", "Each edge.", "Linear total."], "subject": "computer_science", "text": "Answer: Nodes plus edges.\nSteps:\n1. Each node.\n2. Each edge.\n3. Linear total.", "topic": "complexity"}
{"answer": "Chaining stores colliding keys in per-slot lists.", "choices": null, "id": "cs_0475", "kind": "concept", "lang": "en", "question": "What is chaining?", "steps": ["Hash slot.", "List chain.", "Simple."], "subject": "computer_science", "text": "Answer: Bucket lists.\nSteps:\n1. Hash slot.\n2. List chain.\n3. Simple.", "topic": "data_structures"}
{"answer": "Pickling serializes objects to bytes with pickle.", "choices": null, "id": "cs_0476", "kind": "concept", "lang": "en", "question": "What is pickling?", "steps": ["Dump to bytes.", "Load back.", "Keeps structure."], "subject": "computer_science", "text": "Answer: Serialize objects.\nSteps:\n1. Dump to bytes.\n2. Load back.\n3. Keeps structure.", "topic": "python"}
{"answer": "A closure is a function remembering its outer scope variables.", "choices": null, "id": "cs_0477", "kind": "concept", "lang": "en", "question": "What is a closure?", "steps": ["Inner keeps outer.", "Even after return.", "State private."], "subject": "computer_science", "text": "Answer: Remembered scope.\nSteps:\n1. Inner keeps outer.\n2. Even after return.\n3. State private.", "topic": "javascript"}
{"answer": "SELECT returns 90.", "choices": null, "id": "cs_0478", "kind": "worked_example", "lang": "en", "question": "What does SELECT 9 * 10 return?", "steps": ["Multiply.", "9x10=90.", "90."], "subject": "computer_science", "text": "Answer: 90.\nSteps:\n1. Multiply.\n2. 9x10=90.\n3. 90.", "topic": "sql"}
{"answer": "DHCP přiděluje IP adresy automaticky.", "choices": null, "id": "cs_0479", "kind": "concept", "lang": "cs", "question": "Co je DHCP?", "steps": ["Objev.", "Nabídka.", "Obnova."], "subject": "computer_science", "text": "Answer: Auto adresy.\nSteps:\n1. Objev.\n2. Nabídka.\n3. Obnova.", "topic": "networking"}
{"answer": "Count = 11.", "choices": null, "id": "cs_0480", "kind": "worked_example", "lang": "en", "question": "INSERT 11 rows into empty (case 6). Count?", "steps": ["Start 0.", "Add 11.", "11."], "subject": "computer_science", "text": "Answer: 11.\nSteps:\n1. Start 0.\n2. Add 11.\n3. 11.", "topic": "databases"}
{"answer": "Výpadek je přístup na stránku mimo RAM.", "choices": null, "id": "cs_0481", "kind": "concept", "lang": "cs", "question": "Co je výpadek stránky?", "steps": ["Past kernelu.", "Načti.", "Pokračuj."], "subject": "computer_science", "text": "Answer: Chybějící stránka.\nSteps:\n1. Past kernelu.\n2. Načti.\n3. Pokračuj.", "topic": "operating_systems"}
{"answer": "Balance = 170.", "choices": null, "id": "cs_0482", "kind": "worked_example", "lang": "en", "question": "Balance 140, deposit(30) (case 4). Balance?", "steps": ["Start 140.", "Add 30.", "170."], "subject": "computer_science", "text": "Answer: 170.\nSteps:\n1. Start 140.\n2. Add 30.\n3. 170.", "topic": "oop"}
{"answer": "12 comparisons, not found.", "choices": null, "id": "cs_0483", "kind": "worked_example", "lang": "en", "question": "Linear search 17 in 1..12 (case 4). Comparisons?", "steps": ["Check 12.", "None match.", "12."], "subject": "computer_science", "text": "Answer: 12.\nSteps:\n1. Check 12.\n2. None match.\n3. 12.", "topic": "algorithms"}
{"answer": "Ptá se zda rychlé ověření znamená rychlé řešení.", "choices": null, "id": "cs_0484", "kind": "concept", "lang": "cs", "question": "Co je P vs NP?", "steps": ["P řeší.", "NP ověřuje.", "Otevřené."], "subject": "computer_science", "text": "Answer: Ověř vs řeš.\nSteps:\n1. P řeší.\n2. NP ověřuje.\n3. Otevřené.", "topic": "complexity"}
{"answer": "Red-black trees balance with color rules for O(log n).", "choices": null, "id": "cs_0485", "kind": "concept", "lang": "en", "question": "What is a red-black tree?", "steps": ["Red black.", "Rotate fix.", "Always log."], "subject": "computer_science", "text": "Answer: Color balanced.\nSteps:\n1. Red black.\n2. Rotate fix.\n3. Always log.", "topic": "data_structures"}
{"answer": "d['a'] is 5.", "choices": null, "id": "cs_0486", "kind": "worked_example", "lang": "en", "question": "If d={'a':5}, what is d['a']?", "steps": ["Key a.", "Value 5.", "Result 5."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. Key a.\n2. Value 5.\n3. Result 5.", "topic": "python"}
{"answer": "Result is 'hi6'.", "choices": null, "id": "cs_0487", "kind": "worked_example", "lang": "en", "question": "What does 'Hi6'.toLowerCase() give?", "steps": ["Lowercase.", "'hi6'.", "Result."], "subject": "computer_science", "text": "Answer: 'hi6'.\nSteps:\n1. Lowercase.\n2. 'hi6'.\n3. Result.", "topic": "javascript"}
{"answer": "SELECT returns 17.", "choices": null, "id": "cs_0488", "kind": "worked_example", "lang": "en", "question": "What does SELECT 34 / 2 return?", "steps": ["Divide.", "34/2=17.", "17."], "subject": "computer_science", "text": "Answer: 17.\nSteps:\n1. Divide.\n2. 34/2=17.\n3. 17.", "topic": "sql"}
{"answer": "DNS uses port 53.", "choices": {"A": "22", "B": "53", "C": "21", "D": "25"}, "id": "cs_0489", "kind": "multiple_choice", "lang": "en", "question": "Which port does DNS use? (set 5)", "steps": ["Standard port.", "DNS=53.", "Select option B."], "subject": "computer_science", "text": "Answer: 53.\nSteps:\n1. Standard port.\n2. DNS=53.\n3. Select option B.\nAnswer: (B)", "topic": "networking"}
{"answer": "A is Atomicity.", "choices": {"A": "Consistency", "B": "Isolation", "C": "Durability", "D": "Atomicity"}, "id": "cs_0490", "kind": "multiple_choice", "lang": "en", "question": "What is A in ACID (case 3)?", "steps": ["ACID set.", "A first.", "Select option D."], "subject": "computer_science", "text": "Answer: Atomicity.\nSteps:\n1. ACID set.\n2. A first.\n3. Select option D.\nAnswer: (D)", "topic": "databases"}
{"answer": "Roura spojuje výstup a vstup procesů.", "choices": null, "id": "cs_0491", "kind": "concept", "lang": "cs", "question": "Co je roura (pipe)?", "steps": ["Zápis.", "Čtení.", "Buffer."], "subject": "computer_science", "text": "Answer: Spojený tok.\nSteps:\n1. Zápis.\n2. Čtení.\n3. Buffer.", "topic": "operating_systems"}
{"answer": "Overriding redefines a parent method in a child class.", "choices": null, "id": "cs_0492", "kind": "concept", "lang": "en", "question": "What is method overriding?", "steps": ["Same name.", "Child wins.", "Extends or replaces."], "subject": "computer_science", "text": "Answer: Redefine method.\nSteps:\n1. Same name.\n2. Child wins.\n3. Extends or replaces.", "topic": "oop"}
{"answer": "5-disk needs 31 moves.", "choices": {"A": "31", "B": "15", "C": "63", "D": "25"}, "id": "cs_0493", "kind": "multiple_choice", "lang": "cs", "question": "Kolik tahů pro Hanoi s 5 disky?", "steps": ["2^5-1.", "32-1=31.", "Select option A."], "subject": "computer_science", "text": "Answer: 31.\nSteps:\n1. 2^5-1.\n2. 32-1=31.\n3. Select option A.\nAnswer: (A)", "topic": "algorithms"}
{"answer": "Steps = 6.", "choices": {"A": "5", "B": "7", "C": "6", "D": "64"}, "id": "cs_0494", "kind": "multiple_choice", "lang": "cs", "question": "Binární kroky pro n = 64?", "steps": ["log2=6.", "Halve.", "Select option C."], "subject": "computer_science", "text": "Answer: 6.\nSteps:\n1. log2=6.\n2. Halve.\n3. Select option C.\nAnswer: (C)", "topic": "complexity"}
{"answer": "Order 24,14.", "choices": null, "id": "cs_0495", "kind": "worked_example", "lang": "en", "question": "Push 14,24 then pop twice (case 4). Order?", "steps": ["Top 24.", "Then 14.", "24,14."], "subject": "computer_science", "text": "Answer: 24,14.\nSteps:\n1. Top 24.\n2. Then 14.\n3. 24,14.", "topic": "data_structures"}
{"answer": "sum(range(5)) is 10.", "choices": null, "id": "cs_0496", "kind": "worked_example", "lang": "en", "question": "What does sum(range(5)) return?", "steps": ["0 to 4.", "Sum=10.", "Result 10."], "subject": "computer_science", "text": "Answer: 10.\nSteps:\n1. 0 to 4.\n2. Sum=10.\n3. Result 10.", "topic": "python"}
{"answer": "Repeat gives 'ababab'.", "choices": null, "id": "cs_0497", "kind": "worked_example", "lang": "en", "question": "What does 'ab'.repeat(3) give?", "steps": ["Repeat.", "3x.", "'ababab'."], "subject": "computer_science", "text": "Answer: 'ababab'.\nSteps:\n1. Repeat.\n2. 3x.\n3. 'ababab'.", "topic": "javascript"}
{"answer": "Result is 0.", "choices": null, "id": "cs_0498", "kind": "worked_example", "lang": "en", "question": "Compute SELECT 18 % 3.", "steps": ["Modulo.", "18%3=0.", "0."], "subject": "computer_science", "text": "Answer: 0.\nSteps:\n1. Modulo.\n2. 18%3=0.\n3. 0.", "topic": "sql"}
{"answer": "NAT maps private addresses to one public address.", "choices": null, "id": "cs_0499", "kind": "concept", "lang": "en", "question": "What is NAT?", "steps": ["Many private.", "One public.", "Tracks ports."], "subject": "computer_science", "text": "Answer: Address mapping.\nSteps:\n1. Many private.\n2. One public.\n3. Tracks ports.", "topic": "networking"}
{"answer": "PRIMARY KEY ensures unique rows.", "choices": {"A": "PRIMARY KEY", "B": "FOREIGN KEY", "C": "INDEX", "D": "VIEW"}, "id": "cs_0500", "kind": "multiple_choice", "lang": "en", "question": "Which ensures unique rows (case 4)?", "steps": ["Unique id.", "One per table.", "Select option A."], "subject": "computer_science", "text": "Answer: PRIMARY KEY.\nSteps:\n1. Unique id.\n2. One per table.\n3. Select option A.\nAnswer: (A)", "topic": "databases"}
{"answer": "Cycle = 60 ms.", "choices": null, "id": "cs_0501", "kind": "worked_example", "lang": "en", "question": "Quantum 15 ms, 4 procs (case 2). Cycle?", "steps": ["15x4.", "=60.", "60 ms."], "subject": "computer_science", "text": "Answer: 60.\nSteps:\n1. 15x4.\n2. =60.\n3. 60 ms.", "topic": "operating_systems"}
{"answer": "Kompozice skládá objekt z částí.", "choices": null, "id": "cs_0502", "kind": "concept", "lang": "cs", "question": "Co je kompozice?", "steps": ["Má části.", "Volnější.", "Oproti dědění."], "subject": "computer_science", "text": "Answer: Skládání.\nSteps:\n1. Má části.\n2. Volnější.\n3. Oproti dědění.", "topic": "oop"}
{"answer": "DP řeší podproblémy jednou a znovu je používá.", "choices": null, "id": "cs_0503", "kind": "concept", "lang": "cs", "question": "Co je dynamické programování?", "steps": ["Tabulka.", "Zdola nahoru.", "Optimální části."], "subject": "computer_science", "text": "Answer: Znovu pododpovědi.\nSteps:\n1. Tabulka.\n2. Zdola nahoru.\n3. Optimální části.", "topic": "algorithms"}
{"answer": "About 11.", "choices": null, "id": "cs_0504", "kind": "worked_example", "lang": "en", "question": "Binary steps n=2000 (case 6). About?", "steps": ["log2.", "~11.", "11."], "subject": "computer_science", "text": "Answer: 11.\nSteps:\n1. log2.\n2. ~11.\n3. 11.", "topic": "complexity"}
{"answer": "Both directions.", "choices": {"A": "Forward only", "B": "Random only", "C": "Both directions", "D": "No traversal"}, "id": "cs_0505", "kind": "multiple_choice", "lang": "cs", "question": "Jak chodí obousměrný seznam (případ 2)?", "steps": ["Two links.", "Both ways.", "Select option C."], "subject": "computer_science", "text": "Answer: Both directions.\nSteps:\n1. Two links.\n2. Both ways.\n3. Select option C.\nAnswer: (C)", "topic": "data_structures"}
{"answer": "max is 10.", "choices": null, "id": "cs_0506", "kind": "worked_example", "lang": "en", "question": "What does max([7,10,8]) return?", "steps": ["Compare three.", "Largest 10.", "Result 10."], "subject": "computer_science", "text": "Answer: 10.\nSteps:\n1. Compare three.\n2. Largest 10.\n3. Result 10.", "topic": "python"}
{"answer": "Boolean([]) is true.", "choices": {"A": "true", "B": "false", "C": "0", "D": "1"}, "id": "cs_0507", "kind": "multiple_choice", "lang": "en", "question": "What does Boolean([]) give?", "steps": ["Check falsy.", "Result true.", "Select option A."], "subject": "computer_science", "text": "Answer: true.\nSteps:\n1. Check falsy.\n2. Result true.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "LENGTH is 6.", "choices": null, "id": "cs_0508", "kind": "worked_example", "lang": "en", "question": "Compute SELECT LENGTH('hello9').", "steps": ["Count chars.", "'hello9'.", "6."], "subject": "computer_science", "text": "Answer: 6.\nSteps:\n1. Count chars.\n2. 'hello9'.\n3. 6.", "topic": "sql"}
{"answer": "10.6.0.1 je privátní.", "choices": {"A": "8.8.6.1", "B": "1.1.6.1", "C": "10.6.0.1", "D": "203.0.6.1"}, "id": "cs_0509", "kind": "multiple_choice", "lang": "cs", "question": "Která IP je privátní (sada 6)?", "steps": ["Private ranges.", "10.6.0.1 fits.", "Select option C."], "subject": "computer_science", "text": "Answer: 10.6.0.1.\nSteps:\n1. Privátní rozsahy.\n2. 10.6.0.1 vyhovuje.\n3. Select option C.\nAnswer: (C)", "topic": "networking"}
{"answer": "Returned = 3.", "choices": null, "id": "cs_0510", "kind": "worked_example", "lang": "en", "question": "17 rows, WHERE matches 3 (case 7). Returned?", "steps": ["Total 17.", "Match 3.", "3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Total 17.\n2. Match 3.\n3. 3.", "topic": "databases"}
{"answer": "Mutex ensures one.", "choices": {"A": "Queue", "B": "Array", "C": "Mutex", "D": "File"}, "id": "cs_0511", "kind": "multiple_choice", "lang": "en", "question": "What ensures one access (case 6)?", "steps": ["Lock it.", "One holder.", "Select option C."], "subject": "computer_science", "text": "Answer: Mutex.\nSteps:\n1. Lock it.\n2. One holder.\n3. Select option C.\nAnswer: (C)", "topic": "operating_systems"}
{"answer": "Area = 32.", "choices": null, "id": "cs_0512", "kind": "worked_example", "lang": "en", "question": "Rectangle 8 by 4 (case 5). Area?", "steps": ["8x4.", "=32.", "32."], "subject": "computer_science", "text": "Answer: 32.\nSteps:\n1. 8x4.\n2. =32.\n3. 32.", "topic": "oop"}
{"answer": "factorial(10) is 3628800.", "choices": {"A": "362880", "B": "3628800", "C": "3628900", "D": "100"}, "id": "cs_0513", "kind": "multiple_choice", "lang": "en", "question": "What is factorial(10)?", "steps": ["Multiply down.", "Result 3628800.", "Select option B."], "subject": "computer_science", "text": "Answer: 3628800.\nSteps:\n1. Multiply down.\n2. Result 3628800.\n3. Select option B.\nAnswer: (B)", "topic": "algorithms"}
{"answer": "O(2^n) fastest.", "choices": {"A": "O(n)", "B": "O(n log n)", "C": "O(n^2)", "D": "O(2^n)"}, "id": "cs_0514", "kind": "multiple_choice", "lang": "en", "question": "Which grows fastest (case 3)?", "steps": ["Exponential.", "Beats poly.", "Select option D."], "subject": "computer_science", "text": "Answer: O(2^n).\nSteps:\n1. Exponential.\n2. Beats poly.\n3. Select option D.\nAnswer: (D)", "topic": "complexity"}
{"answer": "Heap backs it.", "choices": {"A": "Stack", "B": "Queue", "C": "Array", "D": "Heap"}, "id": "cs_0515", "kind": "multiple_choice", "lang": "en", "question": "What backs priority queue (case 3)?", "steps": ["Need min.", "Heap gives.", "Select option D."], "subject": "computer_science", "text": "Answer: Heap.\nSteps:\n1. Need min.\n2. Heap gives.\n3. Select option D.\nAnswer: (D)", "topic": "data_structures"}
{"answer": "Výjimka signalizuje chybu a řeší se try/except.", "choices": null, "id": "cs_0516", "kind": "concept", "lang": "cs", "question": "Co je výjimka?", "steps": ["Vznikne chyba.", "Zachytí except.", "Finally uklidí."], "subject": "computer_science", "text": "Answer: Signál chyby.\nSteps:\n1. Vznikne chyba.\n2. Zachytí except.\n3. Finally uklidí.", "topic": "python"}
{"answer": "Destructuring unpacks arrays or objects into variables.", "choices": null, "id": "cs_0517", "kind": "concept", "lang": "en", "question": "What is destructuring?", "steps": ["const [a]=arr.", "const {x}=obj.", "Short code."], "subject": "computer_science", "text": "Answer: Unpack values.\nSteps:\n1. const [a]=arr.\n2. const {x}=obj.\n3. Short code.", "topic": "javascript"}
{"answer": "Agregace spojí řádky v jednu hodnotu.", "choices": null, "id": "cs_0518", "kind": "concept", "lang": "cs", "question": "Co je agregace?", "steps": ["COUNT SUM AVG.", "Mnoho na jednu.", "S GROUP."], "subject": "computer_science", "text": "Answer: Spojení řádků.\nSteps:\n1. COUNT SUM AVG.\n2. Mnoho na jednu.\n3. S GROUP.", "topic": "sql"}
{"answer": "Mask is 255.255.192.0.", "choices": null, "id": "cs_0519", "kind": "worked_example", "lang": "en", "question": "What is mask for /18 (case 4)?", "steps": ["Prefix 18.", "Bits.", "255.255.192.0."], "subject": "computer_science", "text": "Answer: 255.255.192.0.\nSteps:\n1. Prefix 18.\n2. Bits.\n3. 255.255.192.0.", "topic": "networking"}
{"answer": "Optimistic locking checks versions at commit instead of locking.", "choices": null, "id": "cs_0520", "kind": "concept", "lang": "en", "question": "What is optimistic locking?", "steps": ["Read version.", "Write if same.", "Retry else."], "subject": "computer_science", "text": "Answer: Version check.\nSteps:\n1. Read version.\n2. Write if same.\n3. Retry else.", "topic": "databases"}
{"answer": "A page fault occurs when accessed page is not in RAM.", "choices": null, "id": "cs_0521", "kind": "concept", "lang": "en", "question": "What is a page fault?", "steps": ["Trap kernel.", "Load page.", "Resume."], "subject": "computer_science", "text": "Answer: Missing page.\nSteps:\n1. Trap kernel.\n2. Load page.\n3. Resume.", "topic": "operating_systems"}
{"answer": "Value = 12.", "choices": null, "id": "cs_0522", "kind": "worked_example", "lang": "en", "question": "Counter 11, inc() (case 6). Value?", "steps": ["Start 11.", "Plus 1.", "12."], "subject": "computer_science", "text": "Answer: 12.\nSteps:\n1. Start 11.\n2. Plus 1.\n3. 12.", "topic": "oop"}
{"answer": "A heuristic is a practical rule trading optimality for speed.", "choices": null, "id": "cs_0523", "kind": "concept", "lang": "en", "question": "What is a heuristic?", "steps": ["Good enough.", "No guarantee.", "Guides search."], "subject": "computer_science", "text": "Answer: Fast rule.\nSteps:\n1. Good enough.\n2. No guarantee.\n3. Guides search.", "topic": "algorithms"}
{"answer": "Heap insert and pop cost O(log n) by tree height.", "choices": null, "id": "cs_0524", "kind": "concept", "lang": "en", "question": "What is Big-O of heap operations?", "steps": ["Bubble path.", "Height log.", "Root fast."], "subject": "computer_science", "text": "Answer: Log height.\nSteps:\n1. Bubble path.\n2. Height log.\n3. Root fast.", "topic": "complexity"}
{"answer": "Load = 0.64.", "choices": {"A": "0.64", "B": "0.74", "C": "0.54", "D": "0.89"}, "id": "cs_0525", "kind": "multiple_choice", "lang": "en", "question": "Load factor for 9 items in 14 slots?", "steps": ["9/14.", "=0.64.", "Select option A."], "subject": "computer_science", "text": "Answer: 0.64.\nSteps:\n1. 9/14.\n2. =0.64.\n3. Select option A.\nAnswer: (A)", "topic": "data_structures"}
{"answer": "114%5 is 4.", "choices": {"A": "4", "B": "0", "C": "1", "D": "5"}, "id": "cs_0526", "kind": "multiple_choice", "lang": "en", "question": "What does 114 % 5 give in Python?", "steps": ["Remainder.", "114%5=4.", "Select option A."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Remainder.\n2. 114%5=4.\n3. Select option A.\nAnswer: (A)", "topic": "python"}
{"answer": "Math.max is 7.", "choices": {"A": "5", "B": "7", "C": "6", "D": "8"}, "id": "cs_0527", "kind": "multiple_choice", "lang": "en", "question": "What does Math.max(5,6,7) give?", "steps": ["Compare three.", "Largest 7.", "Select option B."], "subject": "computer_science", "text": "Answer: 7.\nSteps:\n1. Compare three.\n2. Largest 7.\n3. Select option B.\nAnswer: (B)", "topic": "javascript"}
{"answer": "MIN is 15.", "choices": null, "id": "cs_0528", "kind": "worked_example", "lang": "en", "question": "Compute SELECT MIN of (15,18).", "steps": ["Compare.", "Smallest 15.", "15."], "subject": "computer_science", "text": "Answer: 15.\nSteps:\n1. Compare.\n2. Smallest 15.\n3. 15.", "topic": "sql"}
{"answer": "UDP je bez spojení.", "choices": {"A": "TCP", "B": "HTTP", "C": "IP", "D": "UDP"}, "id": "cs_0529", "kind": "multiple_choice", "lang": "cs", "question": "Co je bez spojení (případ 7)?", "steps": ["No handshake.", "UDP fits.", "Select option D."], "subject": "computer_science", "text": "Answer: UDP.\nSteps:\n1. Žádný handshake.\n2. UDP vyhovuje.\n3. Select option D.\nAnswer: (D)", "topic": "networking"}
{"answer": "B-tree indexes keep sorted keys for fast range search.", "choices": null, "id": "cs_0530", "kind": "concept", "lang": "en", "question": "What is a B-tree index?", "steps": ["Balanced tree.", "Log search.", "Range easy."], "subject": "computer_science", "text": "Answer: Sorted index.\nSteps:\n1. Balanced tree.\n2. Log search.\n3. Range easy.", "topic": "databases"}
{"answer": "Virtual = 12 GB.", "choices": null, "id": "cs_0531", "kind": "worked_example", "lang": "en", "question": "RAM 7 GB + swap 5 GB (case 3). Virtual?", "steps": ["7+5.", "=12.", "12 GB."], "subject": "computer_science", "text": "Answer: 12.\nSteps:\n1. 7+5.\n2. =12.\n3. 12 GB.", "topic": "operating_systems"}
{"answer": "__init__ constructs.", "choices": {"A": "__len__", "B": "__init__", "C": "__add__", "D": "__str__"}, "id": "cs_0532", "kind": "multiple_choice", "lang": "en", "question": "Which is constructor (case 5)?", "steps": ["Init runs.", "Sets fields.", "Select option B."], "subject": "computer_science", "text": "Answer: __init__.\nSteps:\n1. Init runs.\n2. Sets fields.\n3. Select option B.\nAnswer: (B)", "topic": "oop"}
{"answer": "Sorted = [6, 7, 8].", "choices": null, "id": "cs_0533", "kind": "worked_example", "lang": "en", "question": "Selection-sort [8, 6, 7] (case 5). Result?", "steps": ["Min 6.", "Swap.", "[6, 7, 8]."], "subject": "computer_science", "text": "Answer: [6, 7, 8].\nSteps:\n1. Min 6.\n2. Swap.\n3. [6, 7, 8].", "topic": "algorithms"}
{"answer": "400 vs 160000.", "choices": null, "id": "cs_0534", "kind": "worked_example", "lang": "en", "question": "O(n) vs O(n^2) n=400 (case 7). Steps?", "steps": ["O(n)=400.", "O(n^2)=160000.", "Done."], "subject": "computer_science", "text": "Answer: 400 vs 160000.\nSteps:\n1. O(n)=400.\n2. O(n^2)=160000.\n3. Done.", "topic": "complexity"}
{"answer": "Trie ukládá řetězce podle prefixů.", "choices": null, "id": "cs_0535", "kind": "concept", "lang": "cs", "question": "Co je trie?", "steps": ["Znakové uzly.", "Sdílí začátek.", "Konec slova."], "subject": "computer_science", "text": "Answer: Prefixový strom.\nSteps:\n1. Znakové uzly.\n2. Sdílí začátek.\n3. Konec slova.", "topic": "data_structures"}
{"answer": "A metaclass is the class of a class controlling creation.", "choices": null, "id": "cs_0536", "kind": "concept", "lang": "en", "question": "What is a metaclass?", "steps": ["Type default.", "Custom creation.", "Rare use."], "subject": "computer_science", "text": "Answer: Class of class.\nSteps:\n1. Type default.\n2. Custom creation.\n3. Rare use.", "topic": "python"}
{"answer": "Spread ... expands iterables into elements or args.", "choices": null, "id": "cs_0537", "kind": "concept", "lang": "en", "question": "What is spread syntax?", "steps": ["[...a,1].", "Call f(...a).", "Copy arrays."], "subject": "computer_science", "text": "Answer: Expand items.\nSteps:\n1. [...a,1].\n2. Call f(...a).\n3. Copy arrays.", "topic": "javascript"}
{"answer": "SELECT 9+11 returns 20.", "choices": {"A": "20", "B": "19", "C": "21", "D": "22"}, "id": "cs_0538", "kind": "multiple_choice", "lang": "cs", "question": "Kterou hodnotu vrátí SELECT 9 + 11?", "steps": ["Add.", "9+11=20.", "Select option A."], "subject": "computer_science", "text": "Answer: 20.\nSteps:\n1. Add.\n2. 9+11=20.\n3. Select option A.\nAnswer: (A)", "topic": "sql"}
{"answer": "DHCP assigns IP addresses automatically to hosts.", "choices": null, "id": "cs_0539", "kind": "concept", "lang": "en", "question": "What is DHCP?", "steps": ["Discover.", "Offer address.", "Lease renews."], "subject": "computer_science", "text": "Answer: Auto addresses.\nSteps:\n1. Discover.\n2. Offer address.\n3. Lease renews.", "topic": "networking"}
{"answer": "Eventual consistency promises replicas converge over time.", "choices": null, "id": "cs_0540", "kind": "concept", "lang": "en", "question": "What is eventual consistency?", "steps": ["Write anywhere.", "Sync async.", "Brief stale."], "subject": "computer_science", "text": "Answer: Converge later.\nSteps:\n1. Write anywhere.\n2. Sync async.\n3. Brief stale.", "topic": "databases"}
{"answer": "CPUs = 12.", "choices": null, "id": "cs_0541", "kind": "worked_example", "lang": "en", "question": "6 cores, 2 threads each (case 4). Logical CPUs?", "steps": ["6x2.", "=12.", "12."], "subject": "computer_science", "text": "Answer: 12.\nSteps:\n1. 6x2.\n2. =12.\n3. 12.", "topic": "operating_systems"}
{"answer": "B().x = 9.", "choices": null, "id": "cs_0542", "kind": "worked_example", "lang": "en", "question": "Class A x=9, B(A) (case 7). B().x?", "steps": ["A sets.", "B inherits.", "9."], "subject": "computer_science", "text": "Answer: 9.\nSteps:\n1. A sets.\n2. B inherits.\n3. 9.", "topic": "oop"}
{"answer": "factorial(6) = 720.", "choices": null, "id": "cs_0543", "kind": "worked_example", "lang": "en", "question": "Compute factorial(6) (case 6).", "steps": ["Expand.", "Product.", "720."], "subject": "computer_science", "text": "Answer: 720.\nSteps:\n1. Expand.\n2. Product.\n3. 720.", "topic": "algorithms"}
{"answer": "5 items give 32 subsets.", "choices": {"A": "32", "B": "25", "C": "16", "D": "64"}, "id": "cs_0544", "kind": "multiple_choice", "lang": "en", "question": "How many subsets for 5 items?", "steps": ["2^5.", "=32.", "Select option A."], "subject": "computer_science", "text": "Answer: 32.\nSteps:\n1. 2^5.\n2. =32.\n3. Select option A.\nAnswer: (A)", "topic": "complexity"}
{"answer": "Load = 0.9.", "choices": null, "id": "cs_0545", "kind": "worked_example", "lang": "en", "question": "18 items in 20 slots (case 5). Load?", "steps": ["18/20.", "=0.9.", "0.9."], "subject": "computer_science", "text": "Answer: 0.9.\nSteps:\n1. 18/20.\n2. =0.9.\n3. 0.9.", "topic": "data_structures"}
{"answer": "x becomes [1, 2, 18].", "choices": null, "id": "cs_0546", "kind": "worked_example", "lang": "en", "question": "x=[1,2]; x.append(18). What is x?", "steps": ["Start [1,2].", "Append 18.", "x=[1, 2, 18]."], "subject": "computer_science", "text": "Answer: [1, 2, 18].\nSteps:\n1. Start [1,2].\n2. Append 18.\n3. x=[1, 2, 18].", "topic": "python"}
{"answer": "Async/await writes promises as sequential code with pauses.", "choices": null, "id": "cs_0547", "kind": "concept", "lang": "en", "question": "What is async/await?", "steps": ["Async returns promise.", "Await pauses.", "Try/catch works."], "subject": "computer_science", "text": "Answer: Sequential async.\nSteps:\n1. Async returns promise.\n2. Await pauses.\n3. Try/catch works.", "topic": "javascript"}
{"answer": "Sum is 120.", "choices": null, "id": "cs_0548", "kind": "worked_example", "lang": "en", "question": "Sum 1..15 via SELECT. What value?", "steps": ["n=15.", "n(n+1)/2.", "120."], "subject": "computer_science", "text": "Answer: 120.\nSteps:\n1. n=15.\n2. n(n+1)/2.\n3. 120.", "topic": "sql"}
{"answer": "/13 has 524286 usable.", "choices": null, "id": "cs_0549", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in /13 (case 5)?", "steps": ["Host bits 19.", "2^19=524288.", "Usable 524286."], "subject": "computer_science", "text": "Answer: 524286.\nSteps:\n1. Host bits 19.\n2. 2^19=524288.\n3. Usable 524286.", "topic": "networking"}
{"answer": "Remain = 14.", "choices": null, "id": "cs_0550", "kind": "worked_example", "lang": "en", "question": "Table has 18 rows, DELETE removes 4 (case 8). Remain?", "steps": ["Start 18.", "Minus 4.", "14."], "subject": "computer_science", "text": "Answer: 14.\nSteps:\n1. Start 18.\n2. Minus 4.\n3. 14.", "topic": "databases"}
{"answer": "Faults = 5.", "choices": null, "id": "cs_0551", "kind": "worked_example", "lang": "en", "question": "5 frames empty, refs 1..5 (case 5). Faults?", "steps": ["All miss.", "Count 5.", "5."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. All miss.\n2. Count 5.\n3. 5.", "topic": "operating_systems"}
{"answer": "Balance = 230.", "choices": null, "id": "cs_0552", "kind": "worked_example", "lang": "en", "question": "Balance 180, deposit(50) (case 8). Balance?", "steps": ["Start 180.", "Add 50.", "230."], "subject": "computer_science", "text": "Answer: 230.\nSteps:\n1. Start 180.\n2. Add 50.\n3. 230.", "topic": "oop"}
{"answer": "Backtracking zkouší a vrací neúspěšné cesty.", "choices": null, "id": "cs_0553", "kind": "concept", "lang": "cs", "question": "Co je backtracking?", "steps": ["Krok.", "Rekurze.", "Zpět při failu."], "subject": "computer_science", "text": "Answer: Zkus a vrať.\nSteps:\n1. Krok.\n2. Rekurze.\n3. Zpět při failu.", "topic": "algorithms"}
{"answer": "Iterations = 343.", "choices": {"A": "49", "B": "343", "C": "98", "D": "56"}, "id": "cs_0554", "kind": "multiple_choice", "lang": "cs", "question": "Trojnásobné smyčky n = 7. Kolik iterací?", "steps": ["7^3.", "=343.", "Select option B."], "subject": "computer_science", "text": "Answer: 343.\nSteps:\n1. 7^3.\n2. =343.\n3. Select option B.\nAnswer: (B)", "topic": "complexity"}
{"answer": "Edges = 28.", "choices": null, "id": "cs_0555", "kind": "worked_example", "lang": "en", "question": "Edges in K8 (case 6). Count?", "steps": ["n(n-1)/2.", "=28.", "28."], "subject": "computer_science", "text": "Answer: 28.\nSteps:\n1. n(n-1)/2.\n2. =28.\n3. 28.", "topic": "data_structures"}
{"answer": "Monkey patching changes code at runtime by rebinding names.", "choices": null, "id": "cs_0556", "kind": "concept", "lang": "en", "question": "What is monkey patching?", "steps": ["Rebind attr.", "Affects later calls.", "Use sparingly."], "subject": "computer_science", "text": "Answer: Runtime change.\nSteps:\n1. Rebind attr.\n2. Affects later calls.\n3. Use sparingly.", "topic": "python"}
{"answer": "NaN means not-a-number from invalid numeric results.", "choices": null, "id": "cs_0557", "kind": "concept", "lang": "en", "question": "What is NaN?", "steps": ["0/0 gives.", "NaN != NaN.", "Check isNaN."], "subject": "computer_science", "text": "Answer: Invalid number.\nSteps:\n1. 0/0 gives.\n2. NaN != NaN.\n3. Check isNaN.", "topic": "javascript"}
{"answer": "A subquery is a SELECT nested inside another query.", "choices": null, "id": "cs_0558", "kind": "concept", "lang": "en", "question": "What is a subquery?", "steps": ["Inner runs.", "Outer uses.", "In WHERE or FROM."], "subject": "computer_science", "text": "Answer: Nested SELECT.\nSteps:\n1. Inner runs.\n2. Outer uses.\n3. In WHERE or FROM.", "topic": "sql"}
{"answer": "ARP maps IP to MAC.", "choices": {"A": "IP to MAC", "B": "IP to port", "C": "MAC to IP", "D": "Port to MAC"}, "id": "cs_0559", "kind": "multiple_choice", "lang": "en", "question": "What does ARP map (case 8)?", "steps": ["LAN lookup.", "IP to MAC.", "Select option A."], "subject": "computer_science", "text": "Answer: IP to MAC.\nSteps:\n1. LAN lookup.\n2. IP to MAC.\n3. Select option A.\nAnswer: (A)", "topic": "networking"}
{"answer": "INSERT adds rows.", "choices": {"A": "SELECT", "B": "INSERT", "C": "DELETE", "D": "UPDATE"}, "id": "cs_0560", "kind": "multiple_choice", "lang": "cs", "question": "Co přidává řádky (případ 5)?", "steps": ["Write op.", "INSERT fits.", "Select option B."], "subject": "computer_science", "text": "Answer: INSERT.\nSteps:\n1. Write op.\n2. INSERT fits.\n3. Select option B.\nAnswer: (B)", "topic": "databases"}
{"answer": "Kernel manages.", "choices": {"A": "Shell", "B": "App", "C": "Driver", "D": "Kernel"}, "id": "cs_0561", "kind": "multiple_choice", "lang": "en", "question": "What manages resources (case 7)?", "steps": ["Core role.", "CPU mem.", "Select option D."], "subject": "computer_science", "text": "Answer: Kernel.\nSteps:\n1. Core role.\n2. CPU mem.\n3. Select option D.\nAnswer: (D)", "topic": "operating_systems"}
{"answer": "Area = 48.", "choices": null, "id": "cs_0562", "kind": "worked_example", "lang": "en", "question": "Rectangle 6 by 8 (case 9). Area?", "steps": ["6x8.", "=48.", "48."], "subject": "computer_science", "text": "Answer: 48.\nSteps:\n1. 6x8.\n2. =48.\n3. 48.", "topic": "oop"}
{"answer": "Moves = 31.", "choices": null, "id": "cs_0563", "kind": "worked_example", "lang": "en", "question": "Hanoi 5 disks (case 7). Moves?", "steps": ["2^5-1.", "=31.", "31."], "subject": "computer_science", "text": "Answer: 31.\nSteps:\n1. 2^5-1.\n2. =31.\n3. 31.", "topic": "algorithms"}
{"answer": "Steps = 10.", "choices": {"A": "9", "B": "11", "C": "10", "D": "1024"}, "id": "cs_0564", "kind": "multiple_choice", "lang": "en", "question": "Binary steps for n = 1024?", "steps": ["log2=10.", "Halve.", "Select option C."], "subject": "computer_science", "text": "Answer: 10.\nSteps:\n1. log2=10.\n2. Halve.\n3. Select option C.\nAnswer: (C)", "topic": "complexity"}
{"answer": "Returns 12.", "choices": null, "id": "cs_0565", "kind": "worked_example", "lang": "en", "question": "Enqueue 12,13 then dequeue (case 7). Returns?", "steps": ["Front 12.", "FIFO.", "12."], "subject": "computer_science", "text": "Answer: 12.\nSteps:\n1. Front 12.\n2. FIFO.\n3. 12.", "topic": "data_structures"}
{"answer": "sorted([7, 5, 10]) is [5, 7, 10].", "choices": {"A": "[10, 7, 5]", "B": "[5, 7, 10]", "C": "[7, 5, 10]", "D": "[5, 10, 7]"}, "id": "cs_0566", "kind": "multiple_choice", "lang": "en", "question": "What does sorted([7, 5, 10]) give?", "steps": ["Sort ascending.", "Result [5, 7, 10].", "Select option B."], "subject": "computer_science", "text": "Answer: [5, 7, 10].\nSteps:\n1. Sort ascending.\n2. Result [5, 7, 10].\n3. Select option B.\nAnswer: (B)", "topic": "python"}
{"answer": "[6,7].length je 2.", "choices": {"A": "1", "B": "3", "C": "2", "D": "0"}, "id": "cs_0567", "kind": "multiple_choice", "lang": "cs", "question": "Co vrátí [6,7].length?", "steps": ["Two items.", "Length 2.", "Select option C."], "subject": "computer_science", "text": "Answer: 2.\nSteps:\n1. Dva prvky.\n2. Délka je 2.\n3. Select option C.\nAnswer: (C)", "topic": "javascript"}
{"answer": "SELECT returns 240.", "choices": null, "id": "cs_0568", "kind": "worked_example", "lang": "en", "question": "What does SELECT 15 * 16 return?", "steps": ["Multiply.", "15x16=240.", "240."], "subject": "computer_science", "text": "Answer: 240.\nSteps:\n1. Multiply.\n2. 15x16=240.\n3. 240.", "topic": "sql"}
{"answer": "Subnets = 4.", "choices": null, "id": "cs_0569", "kind": "worked_example", "lang": "en", "question": "Split /20 into /22 (case 6). How many subnets?", "steps": ["Bits 2.", "2^2=4.", "4."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Bits 2.\n2. 2^2=4.\n3. 4.", "topic": "networking"}
{"answer": "Index speeds reads.", "choices": {"A": "Deletes data", "B": "Drops table", "C": "Speeds reads", "D": "Stops DB"}, "id": "cs_0570", "kind": "multiple_choice", "lang": "en", "question": "What is an index for (case 6)?", "steps": ["Lookup aid.", "Faster.", "Select option C."], "subject": "computer_science", "text": "Answer: Speeds reads.\nSteps:\n1. Lookup aid.\n2. Faster.\n3. Select option C.\nAnswer: (C)", "topic": "databases"}
{"answer": "Demand paging loads pages only when first accessed.", "choices": null, "id": "cs_0571", "kind": "concept", "lang": "en", "question": "What is demand paging?", "steps": ["Start empty.", "Fault loads.", "Less I/O."], "subject": "computer_science", "text": "Answer: Lazy load.\nSteps:\n1. Start empty.\n2. Fault loads.\n3. Less I/O.", "topic": "operating_systems"}
{"answer": "Abstraktní třída nelze vytvořit a žádá metody.", "choices": null, "id": "cs_0572", "kind": "concept", "lang": "cs", "question": "Co je abstraktní třída?", "steps": ["Nelze make.", "Potomek doplní.", "Vynucuje API."], "subject": "computer_science", "text": "Answer: Nedokončená.\nSteps:\n1. Nelze make.\n2. Potomek doplní.\n3. Vynucuje API.", "topic": "oop"}
{"answer": "A* picks paths by cost plus estimated remaining distance.", "choices": null, "id": "cs_0573", "kind": "concept", "lang": "en", "question": "What is A* search?", "steps": ["g cost so far.", "h estimate.", "Best first."], "subject": "computer_science", "text": "Answer: Cost plus guess.\nSteps:\n1. g cost so far.\n2. h estimate.\n3. Best first.", "topic": "algorithms"}
{"answer": "O(2^n) fastest.", "choices": {"A": "O(n)", "B": "O(n log n)", "C": "O(n^2)", "D": "O(2^n)"}, "id": "cs_0574", "kind": "multiple_choice", "lang": "cs", "question": "Co roste nejrychleji (případ 7)?", "steps": ["Exponential.", "Beats poly.", "Select option D."], "subject": "computer_science", "text": "Answer: O(2^n).\nSteps:\n1. Exponential.\n2. Beats poly.\n3. Select option D.\nAnswer: (D)", "topic": "complexity"}
{"answer": "K8 has 28 edges.", "choices": {"A": "27", "B": "28", "C": "29", "D": "64"}, "id": "cs_0575", "kind": "multiple_choice", "lang": "en", "question": "How many edges in K8?", "steps": ["n(n-1)/2.", "=28.", "Select option B."], "subject": "computer_science", "text": "Answer: 28.\nSteps:\n1. n(n-1)/2.\n2. =28.\n3. Select option B.\nAnswer: (B)", "topic": "data_structures"}
{"answer": "len([6, 7, 8, 9]) is 4.", "choices": {"A": "3", "B": "5", "C": "4", "D": "6"}, "id": "cs_0576", "kind": "multiple_choice", "lang": "en", "question": "What does len([6, 7, 8, 9]) give?", "steps": ["Count items.", "List has {c}.", "Select option C."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Count items.\n2. List has {c}.\n3. Select option C.\nAnswer: (C)", "topic": "python"}
{"answer": "'x' + 10 je 'x10'.", "choices": {"A": "'10x'", "B": "'11'", "C": "10", "D": "'x10'"}, "id": "cs_0577", "kind": "multiple_choice", "lang": "cs", "question": "Co vrátí 'x' + 10?", "steps": ["String concat.", "Result 'x10'.", "Select option D."], "subject": "computer_science", "text": "Answer: 'x10'.\nSteps:\n1. Spojení řetězců.\n2. Výsledek je 'x10'.\n3. Select option D.\nAnswer: (D)", "topic": "javascript"}
{"answer": "SELECT returns 19.", "choices": {"A": "18", "B": "19", "C": "20", "D": "21"}, "id": "cs_0578", "kind": "multiple_choice", "lang": "en", "question": "Which value does SELECT 25 - 6 return?", "steps": ["Subtract.", "25-6=19.", "Select option B."], "subject": "computer_science", "text": "Answer: 19.\nSteps:\n1. Subtract.\n2. 25-6=19.\n3. Select option B.\nAnswer: (B)", "topic": "sql"}
{"answer": "Time = 6 s.", "choices": null, "id": "cs_0579", "kind": "worked_example", "lang": "en", "question": "Download 120 MB at 20 MB/s (case 7). Seconds?", "steps": ["Size 120.", "Rate 20.", "6 s."], "subject": "computer_science", "text": "Answer: 6.\nSteps:\n1. Size 120.\n2. Rate 20.\n3. 6 s.", "topic": "networking"}
{"answer": "CAP says pick two of consistency, availability, partition tolerance.", "choices": null, "id": "cs_0580", "kind": "concept", "lang": "en", "question": "What is CAP theorem?", "steps": ["Network splits.", "Choose side.", "Tradeoff."], "subject": "computer_science", "text": "Answer: Pick two.\nSteps:\n1. Network splits.\n2. Choose side.\n3. Tradeoff.", "topic": "databases"}
{"answer": "Cycle = 60 ms.", "choices": null, "id": "cs_0581", "kind": "worked_example", "lang": "en", "question": "Quantum 15 ms, 4 procs (case 6). Cycle?", "steps": ["15x4.", "=60.", "60 ms."], "subject": "computer_science", "text": "Answer: 60.\nSteps:\n1. 15x4.\n2. =60.\n3. 60 ms.", "topic": "operating_systems"}
{"answer": "Encapsulation bundles.", "choices": {"A": "Loop", "B": "Sort", "C": "Encapsulation", "D": "Search"}, "id": "cs_0582", "kind": "multiple_choice", "lang": "cs", "question": "Co spojuje data a metody (případ 6)?", "steps": ["Hide inside.", "One unit.", "Select option C."], "subject": "computer_science", "text": "Answer: Encapsulation.\nSteps:\n1. Hide inside.\n2. One unit.\n3. Select option C.\nAnswer: (C)", "topic": "oop"}
{"answer": "Steps = 5.", "choices": {"A": "4", "B": "6", "C": "5", "D": "32"}, "id": "cs_0583", "kind": "multiple_choice", "lang": "en", "question": "Binary search steps for n = 32?", "steps": ["log2(32)=5.", "Halve 5x.", "Select option C."], "subject": "computer_science", "text": "Answer: 5.\nSteps:\n1. log2(32)=5.\n2. Halve 5x.\n3. Select option C.\nAnswer: (C)", "topic": "algorithms"}
{"answer": "Hash worst case degrades to O(n) with many collisions.", "choices": null, "id": "cs_0584", "kind": "concept", "lang": "en", "question": "What is Big-O of hash worst case?", "steps": ["All one slot.", "Scan list.", "Rare good hash."], "subject": "computer_science", "text": "Answer: Collision pile.\nSteps:\n1. All one slot.\n2. Scan list.\n3. Rare good hash.", "topic": "complexity"}
{"answer": "Order 28,18.", "choices": null, "id": "cs_0585", "kind": "worked_example", "lang": "en", "question": "Push 18,28 then pop twice (case 8). Order?", "steps": ["Top 28.", "Then 18.", "28,18."], "subject": "computer_science", "text": "Answer: 28,18.\nSteps:\n1. Top 28.\n2. Then 18.\n3. 28,18.", "topic": "data_structures"}
{"answer": "The walrus := assigns and returns a value in one step.", "choices": null, "id": "cs_0586", "kind": "concept", "lang": "en", "question": "What is the walrus operator?", "steps": ["Syntax :=.", "Use in if.", "Saves line."], "subject": "computer_science", "text": "Answer: Assign and return.\nSteps:\n1. Syntax :=.\n2. Use in if.\n3. Saves line.", "topic": "python"}
{"answer": "Undefined means missing while null means intentional empty.", "choices": null, "id": "cs_0587", "kind": "concept", "lang": "en", "question": "What is undefined versus null?", "steps": ["No value yet.", "Null assigned.", "Both falsy."], "subject": "computer_science", "text": "Answer: Missing versus empty.\nSteps:\n1. No value yet.\n2. Null assigned.\n3. Both falsy.", "topic": "javascript"}
{"answer": "SELECT returns 81.", "choices": {"A": "80", "B": "82", "C": "81", "D": "18"}, "id": "cs_0588", "kind": "multiple_choice", "lang": "cs", "question": "Kterou hodnotu vrátí SELECT 9 * 9?", "steps": ["Multiply.", "9x9=81.", "Select option C."], "subject": "computer_science", "text": "Answer: 81.\nSteps:\n1. Multiply.\n2. 9x9=81.\n3. Select option C.\nAnswer: (C)", "topic": "sql"}
{"answer": "Rate = 20.", "choices": null, "id": "cs_0589", "kind": "worked_example", "lang": "en", "question": "RTT 50 ms (case 8). Serial req/s?", "steps": ["1000 ms.", "1000/50=20.", "20."], "subject": "computer_science", "text": "Answer: 20.\nSteps:\n1. 1000 ms.\n2. 1000/50=20.\n3. 20.", "topic": "networking"}
{"answer": "A znamená atomicitu.", "choices": {"A": "Consistency", "B": "Isolation", "C": "Durability", "D": "Atomicity"}, "id": "cs_0590", "kind": "multiple_choice", "lang": "cs", "question": "Co je A v ACID (případ 7)?", "steps": ["ACID set.", "A first.", "Select option D."], "subject": "computer_science", "text": "Answer: Atomicity.\nSteps:\n1. Sada ACID.\n2. A je první.\n3. Select option D.\nAnswer: (D)", "topic": "databases"}
{"answer": "Virtual = 16 GB.", "choices": null, "id": "cs_0591", "kind": "worked_example", "lang": "en", "question": "RAM 11 GB + swap 5 GB (case 7). Virtual?", "steps": ["11+5.", "=16.", "16 GB."], "subject": "computer_science", "text": "Answer: 16.\nSteps:\n1. 11+5.\n2. =16.\n3. 16 GB.", "topic": "operating_systems"}
{"answer": "Subtypes must work wherever their parent type works.", "choices": null, "id": "cs_0592", "kind": "concept", "lang": "en", "question": "What is the Liskov principle?", "steps": ["Same contract.", "No surprises.", "Behavior keeps."], "subject": "computer_science", "text": "Answer: Safe substitute.\nSteps:\n1. Same contract.\n2. No surprises.\n3. Behavior keeps.", "topic": "oop"}
{"answer": "16 comparisons, not found.", "choices": null, "id": "cs_0593", "kind": "worked_example", "lang": "en", "question": "Linear search 21 in 1..16 (case 8). Comparisons?", "steps": ["Check 16.", "None match.", "16."], "subject": "computer_science", "text": "Answer: 16.\nSteps:\n1. Check 16.\n2. None match.\n3. 16.", "topic": "algorithms"}
{"answer": "It asks whether fast checking implies fast solving.", "choices": null, "id": "cs_0594", "kind": "concept", "lang": "en", "question": "What is P versus NP about?", "steps": ["P solves fast.", "NP checks fast.", "Open question."], "subject": "computer_science", "text": "Answer: Check versus solve.\nSteps:\n1. P solves fast.\n2. NP checks fast.\n3. Open question.", "topic": "complexity"}
{"answer": "Both directions.", "choices": {"A": "Forward only", "B": "Random only", "C": "Both directions", "D": "No traversal"}, "id": "cs_0595", "kind": "multiple_choice", "lang": "cs", "question": "Jak chodí obousměrný seznam (případ 6)?", "steps": ["Two links.", "Both ways.", "Select option C."], "subject": "computer_science", "text": "Answer: Both directions.\nSteps:\n1. Two links.\n2. Both ways.\n3. Select option C.\nAnswer: (C)", "topic": "data_structures"}
{"answer": "Type hints annotate expected types without enforcing them.", "choices": null, "id": "cs_0596", "kind": "concept", "lang": "en", "question": "What are type hints?", "steps": ["Syntax x: int.", "Checked by tools.", "Docs help."], "subject": "computer_science", "text": "Answer: Type annotations.\nSteps:\n1. Syntax x: int.\n2. Checked by tools.\n3. Docs help.", "topic": "python"}
{"answer": "18%4 is 2.", "choices": {"A": "2", "B": "3", "C": "0", "D": "4"}, "id": "cs_0597", "kind": "multiple_choice", "lang": "en", "question": "What does 18 % 4 give in JavaScript?", "steps": ["Remainder.", "18%4=2.", "Select option A."], "subject": "computer_science", "text": "Answer: 2.\nSteps:\n1. Remainder.\n2. 18%4=2.\n3. Select option A.\nAnswer: (A)", "topic": "javascript"}
{"answer": "LIKE matches text patterns with % and _.", "choices": null, "id": "cs_0598", "kind": "concept", "lang": "en", "question": "What is LIKE for?", "steps": ["% any run.", "_ one char.", "Case varies."], "subject": "computer_science", "text": "Answer: Pattern match.\nSteps:\n1. % any run.\n2. _ one char.\n3. Case varies.", "topic": "sql"}
{"answer": "ARP maps IP addresses to MAC addresses on LAN.", "choices": null, "id": "cs_0599", "kind": "concept", "lang": "en", "question": "What is ARP?", "steps": ["Who has IP.", "Reply MAC.", "Cache it."], "subject": "computer_science", "text": "Answer: IP to MAC.\nSteps:\n1. Who has IP.\n2. Reply MAC.\n3. Cache it.", "topic": "networking"}
{"answer": "Replikace kopíruje data na více serverů.", "choices": null, "id": "cs_0600", "kind": "concept", "lang": "cs", "question": "Co je replikace?", "steps": ["Primár píše.", "Repliky čtou.", "Bezpečnost."], "subject": "computer_science", "text": "Answer: Kopie dat.\nSteps:\n1. Primár píše.\n2. Repliky čtou.\n3. Bezpečnost.", "topic": "databases"}
{"answer": "Segmentation splits memory by logical units like code and stack.", "choices": null, "id": "cs_0601", "kind": "concept", "lang": "en", "question": "What is segmentation?", "steps": ["Variable sizes.", "Base plus limit.", "External gaps."], "subject": "computer_science", "text": "Answer: Logical units.\nSteps:\n1. Variable sizes.\n2. Base plus limit.\n3. External gaps.", "topic": "operating_systems"}
{"answer": "Inheritance reuses.", "choices": {"A": "Loop", "B": "Recursion", "C": "Sorting", "D": "Inheritance"}, "id": "cs_0602", "kind": "multiple_choice", "lang": "en", "question": "Which reuses parent behavior (case 7)?", "steps": ["Child extends.", "Gets methods.", "Select option D."], "subject": "computer_science", "text": "Answer: Inheritance.\nSteps:\n1. Child extends.\n2. Gets methods.\n3. Select option D.\nAnswer: (D)", "topic": "oop"}
{"answer": "Bubble sort swaps adjacent.", "choices": {"A": "Merge sort", "B": "Binary search", "C": "BFS", "D": "Bubble sort"}, "id": "cs_0603", "kind": "multiple_choice", "lang": "cs", "question": "Co prohazuje sousedy (případ 7)?", "steps": ["Neighbor pairs.", "Swap if wrong.", "Select option D."], "subject": "computer_science", "text": "Answer: Bubble sort.\nSteps:\n1. Neighbor pairs.\n2. Swap if wrong.\n3. Select option D.\nAnswer: (D)", "topic": "algorithms"}
{"answer": "Iterations = 400.", "choices": null, "id": "cs_0604", "kind": "worked_example", "lang": "en", "question": "Nested loops n=20 (case 8). Iterations?", "steps": ["20x20.", "=400.", "400."], "subject": "computer_science", "text": "Answer: 400.\nSteps:\n1. 20x20.\n2. =400.\n3. 400.", "topic": "complexity"}
{"answer": "Heap backs it.", "choices": {"A": "Stack", "B": "Queue", "C": "Array", "D": "Heap"}, "id": "cs_0605", "kind": "multiple_choice", "lang": "en", "question": "What backs priority queue (case 7)?", "steps": ["Need min.", "Heap gives.", "Select option D."], "subject": "computer_science", "text": "Answer: Heap.\nSteps:\n1. Need min.\n2. Heap gives.\n3. Select option D.\nAnswer: (D)", "topic": "data_structures"}
{"answer": "17//4 is 4.", "choices": {"A": "5", "B": "3", "C": "6", "D": "4"}, "id": "cs_0606", "kind": "multiple_choice", "lang": "en", "question": "What does 17 // 4 give in Python?", "steps": ["Floor divide.", "17//4=4.", "Select option D."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Floor divide.\n2. 17//4=4.\n3. Select option D.\nAnswer: (D)", "topic": "python"}
{"answer": "Math.floor(8.7) is 8.", "choices": null, "id": "cs_0607", "kind": "worked_example", "lang": "en", "question": "What does Math.floor(8.7) give?", "steps": ["Round down.", "8.7 to 8.", "8."], "subject": "computer_science", "text": "Answer: 8.\nSteps:\n1. Round down.\n2. 8.7 to 8.\n3. 8.", "topic": "javascript"}
{"answer": "BETWEEN filters values within an inclusive range.", "choices": null, "id": "cs_0608", "kind": "concept", "lang": "en", "question": "What is BETWEEN?", "steps": ["Low and high.", "Includes ends.", "Numbers or dates."], "subject": "computer_science", "text": "Answer: Inclusive range.\nSteps:\n1. Low and high.\n2. Includes ends.\n3. Numbers or dates.", "topic": "sql"}
{"answer": "ICMP carries control messages like ping and errors.", "choices": null, "id": "cs_0609", "kind": "concept", "lang": "en", "question": "What is ICMP?", "steps": ["Echo ping.", "Errors back.", "No ports."], "subject": "computer_science", "text": "Answer: Control messages.\nSteps:\n1. Echo ping.\n2. Errors back.\n3. No ports.", "topic": "networking"}
{"answer": "A stored procedure is saved server-side logic run by call.", "choices": null, "id": "cs_0610", "kind": "concept", "lang": "en", "question": "What is a stored procedure?", "steps": ["Stored code.", "Called often.", "Less roundtrip."], "subject": "computer_science", "text": "Answer: Saved logic.\nSteps:\n1. Stored code.\n2. Called often.\n3. Less roundtrip.", "topic": "databases"}
{"answer": "FIFO evicts oldest.", "choices": {"A": "FIFO", "B": "LIFO", "C": "LRU", "D": "Random"}, "id": "cs_0611", "kind": "multiple_choice", "lang": "cs", "question": "Co vyhazuje nejstarší (případ 8)?", "steps": ["Queue order.", "Oldest first.", "Select option A."], "subject": "computer_science", "text": "Answer: FIFO.\nSteps:\n1. Queue order.\n2. Oldest first.\n3. Select option A.\nAnswer: (A)", "topic": "operating_systems"}
{"answer": "Value = 16.", "choices": null, "id": "cs_0612", "kind": "worked_example", "lang": "en", "question": "Counter 15, inc() (case 10). Value?", "steps": ["Start 15.", "Plus 1.", "16."], "subject": "computer_science", "text": "Answer: 16.\nSteps:\n1. Start 15.\n2. Plus 1.\n3. 16.", "topic": "oop"}
{"answer": "A property exposes a method as attribute access with @property.", "choices": null, "id": "cs_0613", "kind": "concept", "lang": "en", "question": "What is a property?", "steps": ["Getter defined.", "Access no parens.", "Setter optional."], "subject": "computer_science", "text": "Answer: Method as attribute.\nSteps:\n1. Getter defined.\n2. Access no parens.\n3. Setter optional.", "topic": "python"}
{"answer": "9+19 is 28.", "choices": null, "id": "cs_0614", "kind": "worked_example", "lang": "en", "question": "What does 9 + 19 give in JavaScript?", "steps": ["Add.", "=28.", "28."], "subject": "computer_science", "text": "Answer: 28.\nSteps:\n1. Add.\n2. =28.\n3. 28.", "topic": "javascript"}
{"answer": "CASE returns values by conditional branches.", "choices": null, "id": "cs_0615", "kind": "concept", "lang": "en", "question": "What is a CASE expression?", "steps": ["WHEN checks.", "THEN gives.", "ELSE default."], "subject": "computer_science", "text": "Answer: Conditional value.\nSteps:\n1. WHEN checks.\n2. THEN gives.\n3. ELSE default.", "topic": "sql"}
{"answer": "TCP opens SYN, SYN-ACK, ACK.", "choices": {"A": "SYN, ACK", "B": "SYN, SYN-ACK, ACK", "C": "ACK, FIN", "D": "SYN, FIN"}, "id": "cs_0616", "kind": "multiple_choice", "lang": "cs", "question": "Jaké je pořadí TCP (případ 9)?", "steps": ["Three steps.", "In order.", "Select option B."], "subject": "computer_science", "text": "Answer: SYN, SYN-ACK, ACK.\nSteps:\n1. Three steps.\n2. In order.\n3. Select option B.\nAnswer: (B)", "topic": "networking"}
{"answer": "PRIMARY KEY ensures unique rows.", "choices": {"A": "PRIMARY KEY", "B": "FOREIGN KEY", "C": "INDEX", "D": "VIEW"}, "id": "cs_0617", "kind": "multiple_choice", "lang": "en", "question": "Which ensures unique rows (case 8)?", "steps": ["Unique id.", "One per table.", "Select option A."], "subject": "computer_science", "text": "Answer: PRIMARY KEY.\nSteps:\n1. Unique id.\n2. One per table.\n3. Select option A.\nAnswer: (A)", "topic": "databases"}
{"answer": "Round-robin uses slices.", "choices": {"A": "FIFO", "B": "Round-robin", "C": "LIFO", "D": "Stack"}, "id": "cs_0618", "kind": "multiple_choice", "lang": "en", "question": "Which uses time slices (case 9)?", "steps": ["Rotate tasks.", "Fixed quantum.", "Select option B."], "subject": "computer_science", "text": "Answer: Round-robin.\nSteps:\n1. Rotate tasks.\n2. Fixed quantum.\n3. Select option B.\nAnswer: (B)", "topic": "operating_systems"}
{"answer": "super() calls parent.", "choices": {"A": "Calls parent", "B": "Creates child", "C": "Deletes obj", "D": "Copies list"}, "id": "cs_0619", "kind": "multiple_choice", "lang": "en", "question": "What does super() do (case 8)?", "steps": ["Parent link.", "Call method.", "Select option A."], "subject": "computer_science", "text": "Answer: Calls parent.\nSteps:\n1. Parent link.\n2. Call method.\n3. Select option A.\nAnswer: (A)", "topic": "oop"}
{"answer": "18%5 je 3.", "choices": {"A": "3", "B": "4", "C": "0", "D": "5"}, "id": "cs_0620", "kind": "multiple_choice", "lang": "cs", "question": "Co vrátí 18 % 5 v Pythonu?", "steps": ["Zbytek.", "18%5=3.", "Vyber možnost A."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. Zbytek.\n2. 18%5=3.\n3. Vyber možnost A.\nAnswer: (A)", "topic": "python"}
{"answer": "Join gives '10-11-12'.", "choices": null, "id": "cs_0621", "kind": "worked_example", "lang": "en", "question": "What does [10,11,12].join('-') give?", "steps": ["Join dash.", "Parts.", "'10-11-12'."], "subject": "computer_science", "text": "Answer: '10-11-12'.\nSteps:\n1. Join dash.\n2. Parts.\n3. '10-11-12'.", "topic": "javascript"}
{"answer": "MAX je 12.", "choices": {"A": "10", "B": "11", "C": "13", "D": "12"}, "id": "cs_0622", "kind": "multiple_choice", "lang": "cs", "question": "Kterou hodnotu dá SELECT MAX z (10,12,11)?", "steps": ["Compare.", "Largest 12.", "Select option D."], "subject": "computer_science", "text": "Answer: 12.\nSteps:\n1. Porovnej.\n2. Největší je 12.\n3. Select option D.\nAnswer: (D)", "topic": "sql"}
{"answer": "DNS uses port 53.", "choices": {"A": "22", "B": "21", "C": "53", "D": "25"}, "id": "cs_0623", "kind": "multiple_choice", "lang": "en", "question": "Which port does DNS use? (set 10)", "steps": ["Standard port.", "DNS=53.", "Select option C."], "subject": "computer_science", "text": "Answer: 53.\nSteps:\n1. Standard port.\n2. DNS=53.\n3. Select option C.\nAnswer: (C)", "topic": "networking"}
{"answer": "Max = 24.", "choices": null, "id": "cs_0624", "kind": "worked_example", "lang": "en", "question": "Cross-join 6 and 4 rows (case 9). Max?", "steps": ["6x4.", "=24.", "24."], "subject": "computer_science", "text": "Answer: 24.\nSteps:\n1. 6x4.\n2. =24.\n3. 24.", "topic": "databases"}
{"answer": "CPUs = 8.", "choices": null, "id": "cs_0625", "kind": "worked_example", "lang": "en", "question": "4 cores, 2 threads each (case 8). Logical CPUs?", "steps": ["4x2.", "=8.", "8."], "subject": "computer_science", "text": "Answer: 8.\nSteps:\n1. 4x2.\n2. =8.\n3. 8.", "topic": "operating_systems"}
{"answer": "B().x = 13.", "choices": null, "id": "cs_0626", "kind": "worked_example", "lang": "en", "question": "Class A x=13, B(A) (case 11). B().x?", "steps": ["A sets.", "B inherits.", "13."], "subject": "computer_science", "text": "Answer: 13.\nSteps:\n1. A sets.\n2. B inherits.\n3. 13.", "topic": "oop"}
{"answer": "N-tice je neměnný uspořádaný záznam.", "choices": null, "id": "cs_0627", "kind": "concept", "lang": "cs", "question": "Co je n-tice?", "steps": ["Pořadí drží.", "Nelze měnit.", "Příklad: (1,2)."], "subject": "computer_science", "text": "Answer: Neměnný záznam.\nSteps:\n1. Pořadí drží.\n2. Nelze měnit.\n3. Příklad: (1,2).", "topic": "python"}
{"answer": "Result is 'hi11'.", "choices": null, "id": "cs_0628", "kind": "worked_example", "lang": "en", "question": "What does 'Hi11'.toLowerCase() give?", "steps": ["Lowercase.", "'hi11'.", "Result."], "subject": "computer_science", "text": "Answer: 'hi11'.\nSteps:\n1. Lowercase.\n2. 'hi11'.\n3. Result.", "topic": "javascript"}
{"answer": "UNION dedupes combined rows while UNION ALL keeps all.", "choices": null, "id": "cs_0629", "kind": "concept", "lang": "en", "question": "What is UNION versus UNION ALL?", "steps": ["Both stack.", "UNION unique.", "ALL faster."], "subject": "computer_science", "text": "Answer: Dedupe versus keep.\nSteps:\n1. Both stack.\n2. UNION unique.\n3. ALL faster.", "topic": "sql"}
{"answer": "A firewall filters packets by rules to block threats.", "choices": null, "id": "cs_0630", "kind": "concept", "lang": "en", "question": "What is a firewall?", "steps": ["Allow list.", "Deny rest.", "Stateful tracks."], "subject": "computer_science", "text": "Answer: Packet filter.\nSteps:\n1. Allow list.\n2. Deny rest.\n3. Stateful tracks.", "topic": "networking"}
{"answer": "Count = 15.", "choices": null, "id": "cs_0631", "kind": "worked_example", "lang": "en", "question": "INSERT 15 rows into empty (case 10). Count?", "steps": ["Start 0.", "Add 15.", "15."], "subject": "computer_science", "text": "Answer: 15.\nSteps:\n1. Start 0.\n2. Add 15.\n3. 15.", "topic": "databases"}
{"answer": "Faults = 3.", "choices": null, "id": "cs_0632", "kind": "worked_example", "lang": "en", "question": "3 frames empty, refs 1..3 (case 9). Faults?", "steps": ["All miss.", "Count 3.", "3."], "subject": "computer_science", "text": "Answer: 3.\nSteps:\n1. All miss.\n2. Count 3.\n3. 3.", "topic": "operating_systems"}
{"answer": "A static method needs no instance or class state.", "choices": null, "id": "cs_0633", "kind": "concept", "lang": "en", "question": "What is a static method?", "steps": ["Decorator static.", "Call via class.", "Utility fn."], "subject": "computer_science", "text": "Answer: No self.\nSteps:\n1. Decorator static.\n2. Call via class.\n3. Utility fn.", "topic": "oop"}
{"answer": "A shallow copy copies outer container but shares nested objects.", "choices": null, "id": "cs_0634", "kind": "concept", "lang": "en", "question": "What is a shallow copy?", "steps": ["Copy top.", "Nested shared.", "Use copy()."], "subject": "computer_science", "text": "Answer: Outer copy.\nSteps:\n1. Copy top.\n2. Nested shared.\n3. Use copy().", "topic": "python"}
{"answer": "JSON.stringify converts values to JSON text.", "choices": null, "id": "cs_0635", "kind": "concept", "lang": "en", "question": "What is JSON.stringify?", "steps": ["Object in.", "String out.", "Inverse parse."], "subject": "computer_science", "text": "Answer: To JSON text.\nSteps:\n1. Object in.\n2. String out.\n3. Inverse parse.", "topic": "javascript"}
{"answer": "COALESCE returns the first non-NULL argument.", "choices": null, "id": "cs_0636", "kind": "concept", "lang": "en", "question": "What is COALESCE?", "steps": ["Scan args.", "Skip NULL.", "Default last."], "subject": "computer_science", "text": "Answer: First non-NULL.\nSteps:\n1. Scan args.\n2. Skip NULL.\n3. Default last.", "topic": "sql"}
{"answer": "172.16.11.1 je privátní.", "choices": {"A": "8.8.11.1", "B": "1.1.11.1", "C": "203.0.11.1", "D": "172.16.11.1"}, "id": "cs_0637", "kind": "multiple_choice", "lang": "cs", "question": "Která IP je privátní (sada 11)?", "steps": ["Private ranges.", "172.16.11.1 fits.", "Select option D."], "subject": "computer_science", "text": "Answer: 172.16.11.1.\nSteps:\n1. Privátní rozsahy.\n2. 172.16.11.1 vyhovuje.\n3. Select option D.\nAnswer: (D)", "topic": "networking"}
{"answer": "A trigger runs automatically on row changes.", "choices": null, "id": "cs_0638", "kind": "concept", "lang": "en", "question": "What is a trigger?", "steps": ["On insert.", "On update.", "Keeps rules."], "subject": "computer_science", "text": "Answer: Auto action.\nSteps:\n1. On insert.\n2. On update.\n3. Keeps rules.", "topic": "databases"}
{"answer": "Mutex ensures one.", "choices": {"A": "Queue", "B": "Array", "C": "Mutex", "D": "File"}, "id": "cs_0639", "kind": "multiple_choice", "lang": "en", "question": "What ensures one access (case 10)?", "steps": ["Lock it.", "One holder.", "Select option C."], "subject": "computer_science", "text": "Answer: Mutex.\nSteps:\n1. Lock it.\n2. One holder.\n3. Select option C.\nAnswer: (C)", "topic": "operating_systems"}
{"answer": "__init__ constructs.", "choices": {"A": "__len__", "B": "__init__", "C": "__add__", "D": "__str__"}, "id": "cs_0640", "kind": "multiple_choice", "lang": "en", "question": "Which is constructor (case 9)?", "steps": ["Init runs.", "Sets fields.", "Select option B."], "subject": "computer_science", "text": "Answer: __init__.\nSteps:\n1. Init runs.\n2. Sets fields.\n3. Select option B.\nAnswer: (B)", "topic": "oop"}
{"answer": "2**7 is 128.", "choices": {"A": "64", "B": "128", "C": "256", "D": "14"}, "id": "cs_0641", "kind": "multiple_choice", "lang": "en", "question": "What does 2**7 give?", "steps": ["Power of two.", "2**7=128.", "Select option B."], "subject": "computer_science", "text": "Answer: 128.\nSteps:\n1. Power of two.\n2. 2**7=128.\n3. Select option B.\nAnswer: (B)", "topic": "python"}
{"answer": "A callback is a function passed to run later.", "choices": null, "id": "cs_0642", "kind": "concept", "lang": "en", "question": "What is a callback?", "steps": ["Pass fn.", "Called back.", "Async or sync."], "subject": "computer_science", "text": "Answer: Later function.\nSteps:\n1. Pass fn.\n2. Called back.\n3. Async or sync.", "topic": "javascript"}
{"answer": "NULL means unknown so comparisons yield unknown, not true.", "choices": null, "id": "cs_0643", "kind": "concept", "lang": "en", "question": "How does NULL compare?", "steps": ["NULL = NULL unknown.", "Use IS NULL.", "Filter carefully."], "subject": "computer_science", "text": "Answer: Unknown logic.\nSteps:\n1. NULL = NULL unknown.\n2. Use IS NULL.\n3. Filter carefully.", "topic": "sql"}
{"answer": "NAT mapuje privátní adresy na veřejnou.", "choices": null, "id": "cs_0644", "kind": "concept", "lang": "cs", "question": "Co je NAT?", "steps": ["Mnoho na jednu.", "Sleduje porty.", "Šetří IP."], "subject": "computer_science", "text": "Answer: Mapování adres.\nSteps:\n1. Mnoho na jednu.\n2. Sleduje porty.\n3. Šetří IP.", "topic": "networking"}
{"answer": "INSERT adds rows.", "choices": {"A": "SELECT", "B": "INSERT", "C": "DELETE", "D": "UPDATE"}, "id": "cs_0645", "kind": "multiple_choice", "lang": "cs", "question": "Co přidává řádky (případ 9)?", "steps": ["Write op.", "INSERT fits.", "Select option B."], "subject": "computer_science", "text": "Answer: INSERT.\nSteps:\n1. Write op.\n2. INSERT fits.\n3. Select option B.\nAnswer: (B)", "topic": "databases"}
{"answer": "A bootloader loads the kernel at power-on.", "choices": null, "id": "cs_0646", "kind": "concept", "lang": "en", "question": "What is a bootloader?", "steps": ["Firmware runs.", "Load kernel.", "Jump entry."], "subject": "computer_science", "text": "Answer: Start loader.\nSteps:\n1. Firmware runs.\n2. Load kernel.\n3. Jump entry.", "topic": "operating_systems"}
{"answer": "A class method receives the class as first argument.", "choices": null, "id": "cs_0647", "kind": "concept", "lang": "en", "question": "What is a class method?", "steps": ["Decorator class.", "Factory use.", "Alt constructor."], "subject": "computer_science", "text": "Answer: Gets cls.\nSteps:\n1. Decorator class.\n2. Factory use.\n3. Alt constructor.", "topic": "oop"}
{"answer": "Result is [11, 12, 13].", "choices": null, "id": "cs_0648", "kind": "worked_example", "lang": "en", "question": "What does list(range(11,14)) give?", "steps": ["From 11.", "To 13.", "[11, 12, 13]."], "subject": "computer_science", "text": "Answer: [11, 12, 13].\nSteps:\n1. From 11.\n2. To 13.\n3. [11, 12, 13].", "topic": "python"}
{"answer": "Uzávěr je funkce pamatující si vnější proměnné.", "choices": null, "id": "cs_0649", "kind": "concept", "lang": "cs", "question": "Co je uzávěr?", "steps": ["Vnitřní drží.", "Po návratu.", "Soukromý stav."], "subject": "computer_science", "text": "Answer: Pamatuje okolí.\nSteps:\n1. Vnitřní drží.\n2. Po návratu.\n3. Soukromý stav.", "topic": "javascript"}
{"answer": "SELECT 13+15 returns 28.", "choices": {"A": "28", "B": "27", "C": "29", "D": "30"}, "id": "cs_0650", "kind": "multiple_choice", "lang": "cs", "question": "Kterou hodnotu vrátí SELECT 13 + 15?", "steps": ["Add.", "13+15=28.", "Select option A."], "subject": "computer_science", "text": "Answer: 28.\nSteps:\n1. Add.\n2. 13+15=28.\n3. Select option A.\nAnswer: (A)", "topic": "sql"}
{"answer": "Mask is 255.240.0.0.", "choices": null, "id": "cs_0651", "kind": "worked_example", "lang": "en", "question": "What is mask for /12 (case 9)?", "steps": ["Prefix 12.", "Bits.", "255.240.0.0."], "subject": "computer_science", "text": "Answer: 255.240.0.0.\nSteps:\n1. Prefix 12.\n2. Bits.\n3. 255.240.0.0.", "topic": "networking"}
{"answer": "Pooling reuses open connections for many requests.", "choices": null, "id": "cs_0652", "kind": "concept", "lang": "en", "question": "What is connection pooling?", "steps": ["Open once.", "Share queue.", "Less overhead."], "subject": "computer_science", "text": "Answer: Reused links.\nSteps:\n1. Open once.\n2. Share queue.\n3. Less overhead.", "topic": "databases"}
{"answer": "Kernel manages.", "choices": {"A": "Shell", "B": "App", "C": "Driver", "D": "Kernel"}, "id": "cs_0653", "kind": "multiple_choice", "lang": "cs", "question": "Co řídí zdroje (případ 11)?", "steps": ["Core role.", "CPU mem.", "Select option D."], "subject": "computer_science", "text": "Answer: Kernel.\nSteps:\n1. Core role.\n2. CPU mem.\n3. Select option D.\nAnswer: (D)", "topic": "operating_systems"}
{"answer": "Balance = 290.", "choices": null, "id": "cs_0654", "kind": "worked_example", "lang": "en", "question": "Balance 220, deposit(70) (case 12). Balance?", "steps": ["Start 220.", "Add 70.", "290."], "subject": "computer_science", "text": "Answer: 290.\nSteps:\n1. Start 220.\n2. Add 70.\n3. 290.", "topic": "oop"}
{"answer": "'ab'*5 is 'ababababab'.", "choices": null, "id": "cs_0655", "kind": "worked_example", "lang": "en", "question": "What does 'ab'*5 give?", "steps": ["Repeat.", "5x.", "'ababababab'."], "subject": "computer_science", "text": "Answer: 'ababababab'.\nSteps:\n1. Repeat.\n2. 5x.\n3. 'ababababab'.", "topic": "python"}
{"answer": "Repeat gives 'abab'.", "choices": null, "id": "cs_0656", "kind": "worked_example", "lang": "en", "question": "What does 'ab'.repeat(2) give?", "steps": ["Repeat.", "2x.", "'abab'."], "subject": "computer_science", "text": "Answer: 'abab'.\nSteps:\n1. Repeat.\n2. 2x.\n3. 'abab'.", "topic": "javascript"}
{"answer": "GROUP BY groups equal keys for aggregate functions.", "choices": null, "id": "cs_0657", "kind": "concept", "lang": "en", "question": "What is GROUP BY for?", "steps": ["Same key together.", "COUNT or SUM.", "HAVING filters."], "subject": "computer_science", "text": "Answer: Group aggregates.\nSteps:\n1. Same key together.\n2. COUNT or SUM.\n3. HAVING filters.", "topic": "sql"}
{"answer": "Latency is delay while bandwidth is rate of transfer.", "choices": null, "id": "cs_0658", "kind": "concept", "lang": "en", "question": "What is latency versus bandwidth?", "steps": ["Ms delay.", "Mbps rate.", "Both matter."], "subject": "computer_science", "text": "Answer: Delay versus rate.\nSteps:\n1. Ms delay.\n2. Mbps rate.\n3. Both matter.", "topic": "networking"}
{"answer": "Index speeds reads.", "choices": {"A": "Deletes data", "B": "Drops table", "C": "Speeds reads", "D": "Stops DB"}, "id": "cs_0659", "kind": "multiple_choice", "lang": "en", "question": "What is an index for (case 10)?", "steps": ["Lookup aid.", "Faster.", "Select option C."], "subject": "computer_science", "text": "Answer: Speeds reads.\nSteps:\n1. Lookup aid.\n2. Faster.\n3. Select option C.\nAnswer: (C)", "topic": "databases"}
{"answer": "A pipe connects one process output to another input.", "choices": null, "id": "cs_0660", "kind": "concept", "lang": "en", "question": "What is a pipe?", "steps": ["Write end.", "Read end.", "Buffer middle."], "subject": "computer_science", "text": "Answer: Linked stream.\nSteps:\n1. Write end.\n2. Read end.\n3. Buffer middle.", "topic": "operating_systems"}
{"answer": "Multiple inheritance takes behavior from several parents.", "choices": null, "id": "cs_0661", "kind": "concept", "lang": "en", "question": "What is multiple inheritance?", "steps": ["Combine mixins.", "Order MRO.", "Conflicts possible."], "subject": "computer_science", "text": "Answer: Many parents.\nSteps:\n1. Combine mixins.\n2. Order MRO.\n3. Conflicts possible.", "topic": "oop"}
{"answer": "d['a'] is 11.", "choices": null, "id": "cs_0662", "kind": "worked_example", "lang": "en", "question": "If d={'a':11}, what is d['a']?", "steps": ["Key a.", "Value 11.", "Result 11."], "subject": "computer_science", "text": "Answer: 11.\nSteps:\n1. Key a.\n2. Value 11.\n3. Result 11.", "topic": "python"}
{"answer": "Math.floor(13.7) is 13.", "choices": null, "id": "cs_0663", "kind": "worked_example", "lang": "en", "question": "What does Math.floor(13.7) give?", "steps": ["Round down.", "13.7 to 13.", "13."], "subject": "computer_science", "text": "Answer: 13.\nSteps:\n1. Round down.\n2. 13.7 to 13.\n3. 13.", "topic": "javascript"}
{"answer": "LIMIT caps rows and OFFSET skips leading rows.", "choices": null, "id": "cs_0664", "kind": "concept", "lang": "en", "question": "What is LIMIT OFFSET?", "steps": ["LIMIT n.", "OFFSET m.", "Paging."], "subject": "computer_science", "text": "Answer: Cap and skip.\nSteps:\n1. LIMIT n.\n2. OFFSET m.\n3. Paging.", "topic": "sql"}
{"answer": "/7 has 33554430 usable.", "choices": null, "id": "cs_0665", "kind": "worked_example", "lang": "en", "question": "How many usable hosts in /7 (case 10)?", "steps": ["Host bits 25.", "2^25=33554432.", "Usable 33554430."], "subject": "computer_science", "text": "Answer: 33554430.\nSteps:\n1. Host bits 25.\n2. 2^25=33554432.\n3. Usable 33554430.", "topic": "networking"}
{"answer": "Shardování dělí data podle klíče.", "choices": null, "id": "cs_0666", "kind": "concept", "lang": "cs", "question": "Co je shardování?", "steps": ["Klíč směruje.", "Více serverů.", "Škálování."], "subject": "computer_science", "text": "Answer: Dělení dat.\nSteps:\n1. Klíč směruje.\n2. Více serverů.\n3. Škálování.", "topic": "databases"}
{"answer": "Signál je asynchronní oznámení procesu.", "choices": null, "id": "cs_0667", "kind": "concept", "lang": "cs", "question": "Co je signál?", "steps": ["Kill či stop.", "Handler.", "Výchozí jinak."], "subject": "computer_science", "text": "Answer: Async zpráva.\nSteps:\n1. Kill či stop.\n2. Handler.\n3. Výchozí jinak.", "topic": "operating_systems"}
{"answer": "A mixin adds optional behavior to classes.", "choices": null, "id": "cs_0668", "kind": "concept", "lang": "en", "question": "What is a mixin?", "steps": ["Small focused.", "Combined in.", "No alone use."], "subject": "computer_science", "text": "Answer: Added behavior.\nSteps:\n1. Small focused.\n2. Combined in.\n3. No alone use.", "topic": "oop"}
{"answer": "Smyčka spouští frontu callbacků po vyprázdnění zásobníku.", "choices": null, "id": "cs_0669", "kind": "concept", "lang": "cs", "question": "Co je událostní smyčka?", "steps": ["Nejprve stack.", "Pak fronta.", "Async efekt."], "subject": "computer_science", "text": "Answer: Fronta callbacků.\nSteps:\n1. Nejprve stack.\n2. Pak fronta.\n3. Async efekt.", "topic": "javascript"}
{"answer": "SELECT returns 23.", "choices": {"A": "22", "B": "23", "C": "24", "D": "25"}, "id": "cs_0670", "kind": "multiple_choice", "lang": "en", "question": "Which value does SELECT 29 - 6 return?", "steps": ["Subtract.", "29-6=23.", "Select option B."], "subject": "computer_science", "text": "Answer: 23.\nSteps:\n1. Subtract.\n2. 29-6=23.\n3. Select option B.\nAnswer: (B)", "topic": "sql"}
{"answer": "Subnets = 4.", "choices": null, "id": "cs_0671", "kind": "worked_example", "lang": "en", "question": "Split /20 into /22 (case 11). How many subnets?", "steps": ["Bits 2.", "2^2=4.", "4."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. Bits 2.\n2. 2^2=4.\n3. 4.", "topic": "networking"}
{"answer": "Trigger se spustí automaticky při změně.", "choices": null, "id": "cs_0672", "kind": "concept", "lang": "cs", "question": "Co je trigger?", "steps": ["Při insertu.", "Při updatu.", "Pravidla."], "subject": "computer_science", "text": "Answer: Auto akce.\nSteps:\n1. Při insertu.\n2. Při updatu.\n3. Pravidla.", "topic": "databases"}
{"answer": "A signal is an async notification to a process.", "choices": null, "id": "cs_0673", "kind": "concept", "lang": "en", "question": "What is a signal?", "steps": ["Kill or stop.", "Handler runs.", "Default else."], "subject": "computer_science", "text": "Answer: Async notice.\nSteps:\n1. Kill or stop.\n2. Handler runs.\n3. Default else.", "topic": "operating_systems"}
{"answer": "Rozhraní žádá metody bez implementace.", "choices": null, "id": "cs_0674", "kind": "concept", "lang": "cs", "question": "Co je rozhraní?", "steps": ["Jen smlouva.", "Třída splní.", "Více sdílí."], "subject": "computer_science", "text": "Answer: Žádané metody.\nSteps:\n1. Jen smlouva.\n2. Třída splní.\n3. Více sdílí.", "topic": "oop"}
{"answer": "14+29 is 43.", "choices": null, "id": "cs_0675", "kind": "worked_example", "lang": "en", "question": "What does 14 + 29 give in JavaScript?", "steps": ["Add.", "=43.", "43."], "subject": "computer_science", "text": "Answer: 43.\nSteps:\n1. Add.\n2. =43.\n3. 43.", "topic": "javascript"}
{"answer": "SELECT returns 169.", "choices": {"A": "168", "B": "170", "C": "169", "D": "26"}, "id": "cs_0676", "kind": "multiple_choice", "lang": "en", "question": "Which value does SELECT 13 * 13 return?", "steps": ["Multiply.", "13x13=169.", "Select option C."], "subject": "computer_science", "text": "Answer: 169.\nSteps:\n1. Multiply.\n2. 13x13=169.\n3. Select option C.\nAnswer: (C)", "topic": "sql"}
{"answer": "Packet switching routes small packets independently.", "choices": null, "id": "cs_0677", "kind": "concept", "lang": "en", "question": "What is packet switching?", "steps": ["Chop data.", "Route each.", "Reassemble."], "subject": "computer_science", "text": "Answer: Split and route.\nSteps:\n1. Chop data.\n2. Route each.\n3. Reassemble.", "topic": "networking"}
{"answer": "Returned = 7.", "choices": null, "id": "cs_0678", "kind": "worked_example", "lang": "en", "question": "21 rows, WHERE matches 7 (case 11). Returned?", "steps": ["Total 21.", "Match 7.", "7."], "subject": "computer_science", "text": "Answer: 7.\nSteps:\n1. Total 21.\n2. Match 7.\n3. 7.", "topic": "databases"}
{"answer": "Virtualization runs isolated guest machines on one host.", "choices": null, "id": "cs_0679", "kind": "concept", "lang": "en", "question": "What is virtualization?", "steps": ["Hypervisor.", "Share hardware.", "Isolated."], "subject": "computer_science", "text": "Answer: Guest machines.\nSteps:\n1. Hypervisor.\n2. Share hardware.\n3. Isolated.", "topic": "operating_systems"}
{"answer": "Encapsulation bundles.", "choices": {"A": "Loop", "B": "Sort", "C": "Encapsulation", "D": "Search"}, "id": "cs_0680", "kind": "multiple_choice", "lang": "cs", "question": "Co spojuje data a metody (případ 10)?", "steps": ["Hide inside.", "One unit.", "Select option C."], "subject": "computer_science", "text": "Answer: Encapsulation.\nSteps:\n1. Hide inside.\n2. One unit.\n3. Select option C.\nAnswer: (C)", "topic": "oop"}
{"answer": "Math.ceil(9.2) is 10.", "choices": {"A": "9", "B": "10", "C": "11", "D": "8"}, "id": "cs_0681", "kind": "multiple_choice", "lang": "en", "question": "What does Math.ceil(9.2) give?", "steps": ["Round up.", "9.2 to 10.", "Select option B."], "subject": "computer_science", "text": "Answer: 10.\nSteps:\n1. Round up.\n2. 9.2 to 10.\n3. Select option B.\nAnswer: (B)", "topic": "javascript"}
{"answer": "Aggregates combine rows into one value like COUNT or AVG.", "choices": null, "id": "cs_0682", "kind": "concept", "lang": "en", "question": "What is an aggregate?", "steps": ["Many to one.", "COUNT SUM AVG.", "With GROUP."], "subject": "computer_science", "text": "Answer: Row combiner.\nSteps:\n1. Many to one.\n2. COUNT SUM AVG.\n3. With GROUP.", "topic": "sql"}
{"answer": "IPv6 uses 128-bit addresses for huge space.", "choices": null, "id": "cs_0683", "kind": "concept", "lang": "en", "question": "What is IPv6?", "steps": ["Hex groups.", "Many IPs.", "Coexists v4."], "subject": "computer_science", "text": "Answer: Long addresses.\nSteps:\n1. Hex groups.\n2. Many IPs.\n3. Coexists v4.", "topic": "networking"}
{"answer": "Remain = 19.", "choices": null, "id": "cs_0684", "kind": "worked_example", "lang": "en", "question": "Table has 22 rows, DELETE removes 3 (case 12). Remain?", "steps": ["Start 22.", "Minus 3.", "19."], "subject": "computer_science", "text": "Answer: 19.\nSteps:\n1. Start 22.\n2. Minus 3.\n3. 19.", "topic": "databases"}
{"answer": "Cycle = 60 ms.", "choices": null, "id": "cs_0685", "kind": "worked_example", "lang": "en", "question": "Quantum 15 ms, 4 procs (case 10). Cycle?", "steps": ["15x4.", "=60.", "60 ms."], "subject": "computer_science", "text": "Answer: 60.\nSteps:\n1. 15x4.\n2. =60.\n3. 60 ms.", "topic": "operating_systems"}
{"answer": "Area = 28.", "choices": null, "id": "cs_0686", "kind": "worked_example", "lang": "en", "question": "Rectangle 4 by 7 (case 13). Area?", "steps": ["4x7.", "=28.", "28."], "subject": "computer_science", "text": "Answer: 28.\nSteps:\n1. 4x7.\n2. =28.\n3. 28.", "topic": "oop"}
{"answer": "Slib reprezentuje budoucí hodnotu s then/catch.", "choices": null, "id": "cs_0687", "kind": "concept", "lang": "cs", "question": "Co je slib (promise)?", "steps": ["Pending.", "Then/catch.", "Řetězení."], "subject": "computer_science", "text": "Answer: Budoucí hodnota.\nSteps:\n1. Pending.\n2. Then/catch.\n3. Řetězení.", "topic": "javascript"}
{"answer": "SELECT returns 23.", "choices": null, "id": "cs_0688", "kind": "worked_example", "lang": "en", "question": "What does SELECT 46 / 2 return?", "steps": ["Divide.", "46/2=23.", "23."], "subject": "computer_science", "text": "Answer: 23.\nSteps:\n1. Divide.\n2. 46/2=23.\n3. 23.", "topic": "sql"}
{"answer": "Time = 8.5 s.", "choices": null, "id": "cs_0689", "kind": "worked_example", "lang": "en", "question": "Download 170 MB at 20 MB/s (case 12). Seconds?", "steps": ["Size 170.", "Rate 20.", "8.5 s."], "subject": "computer_science", "text": "Answer: 8.5.\nSteps:\n1. Size 170.\n2. Rate 20.\n3. 8.5 s.", "topic": "networking"}
{"answer": "A is Atomicity.", "choices": {"A": "Consistency", "B": "Isolation", "C": "Durability", "D": "Atomicity"}, "id": "cs_0690", "kind": "multiple_choice", "lang": "en", "question": "What is A in ACID (case 11)?", "steps": ["ACID set.", "A first.", "Select option D."], "subject": "computer_science", "text": "Answer: Atomicity.\nSteps:\n1. ACID set.\n2. A first.\n3. Select option D.\nAnswer: (D)", "topic": "databases"}
{"answer": "Virtual = 20 GB.", "choices": null, "id": "cs_0691", "kind": "worked_example", "lang": "en", "question": "RAM 15 GB + swap 5 GB (case 11). Virtual?", "steps": ["15+5.", "=20.", "20 GB."], "subject": "computer_science", "text": "Answer: 20.\nSteps:\n1. 15+5.\n2. =20.\n3. 20 GB.", "topic": "operating_systems"}
{"answer": "Přepsání znovu definuje metodu rodiče.", "choices": null, "id": "cs_0692", "kind": "concept", "lang": "cs", "question": "Co je přepsání metody?", "steps": ["Stejné jméno.", "Potomek vítězí.", "Rozšíří."], "subject": "computer_science", "text": "Answer: Nová definice.\nSteps:\n1. Stejné jméno.\n2. Potomek vítězí.\n3. Rozšíří.", "topic": "oop"}
{"answer": "Boolean('') je false.", "choices": {"A": "true", "B": "0", "C": "false", "D": "1"}, "id": "cs_0693", "kind": "multiple_choice", "lang": "cs", "question": "Co vrátí Boolean('')?", "steps": ["Check falsy.", "Result false.", "Select option C."], "subject": "computer_science", "text": "Answer: false.\nSteps:\n1. Zkontroluj falsy.\n2. Výsledek je false.\n3. Select option C.\nAnswer: (C)", "topic": "javascript"}
{"answer": "Result is 0.", "choices": null, "id": "cs_0694", "kind": "worked_example", "lang": "en", "question": "Compute SELECT 24 % 3.", "steps": ["Modulo.", "24%3=0.", "0."], "subject": "computer_science", "text": "Answer: 0.\nSteps:\n1. Modulo.\n2. 24%3=0.\n3. 0.", "topic": "sql"}
{"answer": "Rate = 20.", "choices": null, "id": "cs_0695", "kind": "worked_example", "lang": "en", "question": "RTT 50 ms (case 13). Serial req/s?", "steps": ["1000 ms.", "1000/50=20.", "20."], "subject": "computer_science", "text": "Answer: 20.\nSteps:\n1. 1000 ms.\n2. 1000/50=20.\n3. 20.", "topic": "networking"}
{"answer": "Max = 20.", "choices": null, "id": "cs_0696", "kind": "worked_example", "lang": "en", "question": "Cross-join 5 and 4 rows (case 13). Max?", "steps": ["5x4.", "=20.", "20."], "subject": "computer_science", "text": "Answer: 20.\nSteps:\n1. 5x4.\n2. =20.\n3. 20.", "topic": "databases"}
{"answer": "CPUs = 4.", "choices": null, "id": "cs_0697", "kind": "worked_example", "lang": "en", "question": "2 cores, 2 threads each (case 12). Logical CPUs?", "steps": ["2x2.", "=4.", "4."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. 2x2.\n2. =4.\n3. 4.", "topic": "operating_systems"}
{"answer": "Inheritance reuses.", "choices": {"A": "Loop", "B": "Recursion", "C": "Sorting", "D": "Inheritance"}, "id": "cs_0698", "kind": "multiple_choice", "lang": "cs", "question": "Co dědí chování (případ 11)?", "steps": ["Child extends.", "Gets methods.", "Select option D."], "subject": "computer_science", "text": "Answer: Inheritance.\nSteps:\n1. Child extends.\n2. Gets methods.\n3. Select option D.\nAnswer: (D)", "topic": "oop"}
{"answer": "Faults = 4.", "choices": null, "id": "cs_0699", "kind": "worked_example", "lang": "en", "question": "4 frames empty, refs 1..4 (case 13). Faults?", "steps": ["All miss.", "Count 4.", "4."], "subject": "computer_science", "text": "Answer: 4.\nSteps:\n1. All miss.\n2. Count 4.\n3. 4.", "topic": "operating_systems"}
{"answer": "Injection passes dependencies from outside instead of creating.", "choices": null, "id": "cs_0700", "kind": "concept", "lang": "en", "question": "What is dependency injection?", "steps": ["Pass in.", "Test easy.", "Loose link."], "subject": "computer_science", "text": "Answer: Outside deps.\nSteps:\n1. Pass in.\n2. Test easy.\n3. Loose link.", "topic": "oop"}