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Your challenge is to, given a matrix of nonnegative integers, remove all rows and columns that contain a 0.
For example, with this matrix:
[[5, 3, 2, 4, 1],
[3, 2, 0, 4, 7],
[7, 1, 9, 8, 2],
[3, 2, 1, 5, 7],
[6, 4, 6, 1, 2],
[9, 3, 2, 4, 0]]
Columns 3 and 5, along with rows 2 and 6 (in bold), contain a 0, so they... |
Challenge
The primitive circle problem is the problem of determining how many coprime integer lattice points \$x,y\$ there are in a circle centered at the origin and with radius \$r \in \mathbb{Z}^+
\$ such that \$x^2+y^2 \le r^2 \$. It's a generalization of Code-Golf: Lattice Points inside a Circle.
Input
Radius \$r... |
Background
Often, when storing a number in binary with some maximum, we simply round the maximum to the next power of two then allocate the number of bits nececairy to store the whole range. Lets call the result of this method \$S(x, m)\$ where x is the number and m is the maximum.
While not bad, the naive has a few bi... |
Challenge
Generate two \$16 \times 16\$ grids, each initially filled with "@" symbols and spaces. Each cell in the grids should be independently filled with an "@" or a space, with each character having an equal probability (\$50\%\$) of being chosen for each cell. This ensures that both grids start off identically, wi... |
Chess960, a.k.a. Fisher random chess, is a variation of the game of chess.
In classic chess the starting positions are always the same. In chess960 they vary.
Before each game of chess960 one random number from 0 to 959 is drawn. Both players then arrange their pieces in the same way according to this number from a loo... |
Even though the concept of phat-fingered-lights-out number should be pretty self-explanatory here is a definition:
Given a nonnegative integer in binary representation a phat-fingered double-bit-flip or phatflip for short replaces a pair of adjacent, equal bits with their complement.
For example given the number 0b1110... |
Problem:
Given a string representing a mathematical expression with constants (pi, e, psi, i), basic arithmetic operations (+, -, *, /), parentheses, fractions, and exponentiation, write a program or function to convert a string to its equivalent LaTeX code. The input string will only contain digits, arithmetic operato... |
Recall from this challenge that a phat-fingered double-bit flip or phatflip is defined as follows:
Given a nonnegative integer in binary representation a phat-fingered
double-bit-flip or phatflip for short replaces a pair of
adjacent, equal bits with their complement.
For example given the number 0b111010010000101
0b1... |
Consider an arbitrary set of letters \$L\$. It may either be \$\{A, B, C\}\$, \$\{M, N, O, P\}\$, \$\{N, F, K, D\}\$, or even contain all the 26 letters. Given an instance of \$L\$ and a positive integer \$n\$, how many \$n\$-letter words can we build from \$L\$ such that no adjacent letters are the same (so for exampl... |
Given a non‑empty string containing only printable ASCII (codepoints 0x20 to 0x7E), write the shortest program or function that swaps the cases of A-Z and a-z.
If a character is in [A-Z], convert it to its lowercase version.
If a character is in [a-z], convert it to its uppercase version.
Otherwise, leave the characte... |
Input: You are given two numbers n and m.
Create the snail: Given an n >= 3, fill an n * n grid with the numbers from 1 to n * n, starting at the top left, going clockwise to the middle like this (for n = 5):
1 2 3 4 5
16 17 18 19 6
15 24 25 20 7
14 23 22 21 8
13 12 11 10 9
Calculate the sum of the neightbour... |
When you leave, my challenges fade to grey, 0A0AE16, 0A0A0AE16...
A while ago, I made this programming language (https://esolangs.org/wiki/Dragostea_din_tei) which uses an interesting number system. It is base two for integers, but for decimals it divides a base two integer by a power of ten.
The input should be a floa... |
Challenge:
Given a 2D array (8x8) of characters, is the enemy king in check?
The program should return true if and only if the king is currently in check.
Standard chess rules apply.
Specifications:
The game is provided using a 2D array,
where blank space means there is not a piece on that square.
You may assume that t... |
Background
As noted in this question, for all positive integers \$n>2\$ there exists at least one Egyptian fraction representation (EFR) of \$n\$ distinct positive integers \$a_{1} < a_{2} < \dots < a_{n}\$ such that $$ \sum_{k=1}^{n} \frac{1}{a_{k}} = 1. \tag{1} \label{1} $$
When \$n=3\$, for instance, we have $$ \fra... |
Given a ragged array, find the length of the largest subarray that contains the depth of that subarray. The base array layer has a depth of 0.
Here is an example:
[1, 2, [3, 4, [2, 5]], 0]
Here, the subarray [2, 5] contains its own depth 2 and has a length of 2 as well.
But in the outermost subarray is a 0, its depth.... |
Introduction
Tensor contraction is an operation that can be performed on a tensor. It is a generalization of the idea of the trace of a matrix. For example, if we have a rank-2 tensor (a matrix) and we contract along both of its axes, we take the sum of each entry in which the indices of these axes are equal. In this c... |
Given a directed graph on the nodes 0, 1, ..n, where each edge has two non-negative integer costs, return the set of all possible Pareto Optimal path costs between node 0 and node n.
These are the costs of paths for which you cannot decrease the first component of the cost without increasing the second component, and c... |
The tetration operation consists of repeated exponentiation, and it is written ↑↑. For instance,
3↑↑3 =3 ^(3^3) = 3^27 = 7,625,597,484,987
A tetrate of two is an integer that is equal to 2↑↑n for some nonnegative integer n. As an edge case, we say that 2↑↑0=1.
In this challenge, you will be given a positive integer as... |
Challenge
The goal of this challenge is to generate and output a \$16 \times 32\$ (height \$\times\$ width) grid where all cells contain a decoy
character, except for a random single cell that contains the target character. The input will be a pair of ASCII (32-126) characters: [target,decoy], where target is the chara... |
Background
This challenge is based on a personal project I did, UnitDC. This challenge is a super-miniaturized version of UnitDC.
Challenge
Please write a simple unit-aware calculator that evaluates a sequence of positive integers, units and operators in RPN (postfix) notation, while checking whether the units are comp... |
A list \$[a_1,a_2,a_3 \cdots a_n]\$ can be uniquely represented as an unordered list of its prefixes - \$ [[a_1],[a_1, a_2], [a_1,a_2,a_3] \cdots [a_1,a_2,a_3 \cdots a_n]] \$. This can be in any order - for example, \$[1, 2, 3]\$ could be represented by any of \$[[1],[1,2],[1,2,3]]\$, \$[[3,2,1],[2,1],[1]]\$, or \$[[2,... |
emanresu A posted a challenge to reconstruct an ordered list of integers from its unordered set of unordered prefixes. Many users (beginning with xnor's answer) noticed that summing each unordered prefix led to a very short solution. Well, let's cruelly take that possibility away by using data that isn't integers!
A fe... |
You work in a kitchen which has a peculiar rule. When you mix something into a pot you must always add at least one new ingredient.
So you can add pasta, oil, salt then pesto, but not pasta, pesto, salt and oil since pesto already contains salt and oil. You only have one pot per dish, so you can't mix ingredients in on... |
Consider a finite, one-dimensional grid where each cell is marked with one of two symbols (I will use the symbols < and >, but you can use other symbols).
When a pinball is placed on one of the cells, it moves according to the following rules:
If the pinball is on a cell that is marked with <, the pinball moves one ce... |
Consider the problem of N queen on an (NxN) chessboard. Two queens are said to attack each other if they are on the same row, column,
or diagonal. Implements backtracking algorithm to solve the problem i.e. place N non-attacking queens on the board.
|
This will be a bit of a different challenge. Back in 2023, I developed a 2D esolang called Electra, and looking back at my hello world program, (which is 582 bytes by the way) I see a lot of room for golfing. There are some topics that aren't covered in the spec, e.g. in which order the currents are generated/interpret... |
I'm currently converting a Float32Array to an Int32Array for input to a real-time audio raw PCM to MP3 recording application.
new Int32Array([...new Float32Array(b)].map(f=>f<0?f*32768:f*32767)
The examples in the wild I've seen convert each float individually to avoid static, gaps, glitches when the audio recording i... |
Consider an \$(n+1) \times (n+1) \$ grid of points places at non-negative integer coordinates. Given two points in the grid at \$(a, b)\$ and \$(c, d)\$, we know that the distance of the first point to the origin at \$(0, 0)\$ is \$x = \sqrt{a^2 + b^2}\$ and the distance of the second point to the origin is \$y = \sqr... |
Imagine you have a positive integer number \$n\$. Let \$m\$ be the number obtained by reversing \$n\$'s digits. If \$m\$ is a whole multiple of \$n\$, then \$n\$ is said to be a reverse divisible number. If neither are a palindrome, \$m\$ is called a palintiple.
For example, \$1089 \cdot 9 = 9801\$, so \$9801\$ is a pa... |
Objective
Given a nonempty unordered list of positive integers, decide whether they can be added, negated, or multiplied to yield a single zero. Each given number must be used exactly once.
There is a taboo. Do not multiply zero to anything. Adding zero to anything is OK.
Examples
Truthy
List, Solution
[1,1], 1-1
[1,1,... |
Challenge
Create a program that outputs a square grid showing visible and non-visible points \$(x, y)\$ from the origin based on their greatest common divisor (GCD).
A point \$(x, y)\$ is considered visible from the origin \$(0, 0)\$ if the \$\gcd(x, y) = 1\$. Otherwise, it's non-visible.
Input
An integer \$n\$, repre... |
You are given an array A of length N and an array B of length N-1.
You need to output array where items alternates:
A[0], B[0], A[1], B[1], ..., B[N-2], A[N-1]
Restrictions:
N>0
Type of items is not specified, but code should work at least for unsigned integers.
Sample input:
A = [1,2,3,4]
B = [7,8,9]
Sample output:... |
Challenge
In this challenge, we will use a language that is very similar to Brainfuck but slightly different.
This variant of BF does not have any input and output commands; instead, it simply takes a tape as input and modifies it until it halts. The final state of the tape is considered the output of the program.
The... |
Background
The newest version of the C standard, C23, adds preprocessor macros like INT_WIDTH, ULONG_WIDTH, and SIZE_WIDTH that tell you the bit width of various integer types (here, int, unsigned long, and size_t, respectively). However, while the majority of us are stuck with pre-C23 compilers/standard libraries, it... |
Challenge
Given ASCII-encoded text input of any size, detect numbers between -1,000,000,000,000,000,000 and 1,000,000,000,000,000,000 exclusive and rewrite them with thousands separators. Use commas only and ignore leading zeroes. Leave the rest of the input unchanged.
Test cases
Input
Output
Description
123
123... |
If I want to type the string aaa, the least keystrokes I can type it in is 3: a a a. But if I want to type the string aaaaaa, I can do it in 5: a a a ctrl-c ctrl-v, where the ctrl-c refers to copying aaa and the ctrl-v refers to pasting it.
Specifically, starting with an empty "buffer" and an empty "clipboard":
The ke... |
In the poker game there are 1277 unique 'High Card' ranks. It's 1287 (13 over 5) if we include all straights.
The challenge is to write a function which returns an integer value corresponding to the rank of each 'High Card' poker combination including all straights. Possible cards are(in ascending order): '23456789TJQK... |
Objective
Given an expression involving ternary values, evaluate it into a ternary value.
Ternary Values
The three truth values in question are the values of Haskell's Ordering, namely LT, EQ, and GT. They stand for "less-than", "equal-to", and "greater-than", respectively. Furthermore, they themselves have an order; L... |
Recursion is actually quite powerful, sometimes its doesn't look like that child problem of itself exist, but recursion is just helpful.
One case per answer.
|
This is the cop's thread, where one should post the scrambled code. Here is the robbers' thread where the cracked source should be posted and linked to the cop's answer.
Task: Write the shortest safe program that given two inputs \$x,y\$, outputs \$\arg(x+iy)\$, where \$\arg(z)\$ is defined as the angle between the po... |
V1.1: Added criterion to help with tiebreakers, a bit overkill but still.
Task: Crack the scrambled code for calculating the argument of a complex number \$z=x+iy\$ given two inputs.
You must post a comment in the cops’ thread with a link to your working source, mentioning clearly that you have cracked it. In your ans... |
Given a collection of coloured laces, what would be the probability, \$P\$, that Alice won't create any loops if, until impossible, they tie two uniformly chosen, free lace ends of differing colours together?
For the avoidance of doubt:
Each lace will be of only one colour and will have precisely two ends.
Alice does ... |
Introduction:
A typical cartoonish cactus usually looks like this:
One big stem in the middle, with some L-shaped branches sticking out.
We'll use this general shape for this challenge.
Challenge:
Given a pair of words, create an ASCII-art cactus with two upside down alphabets as stem. The first word is the left branc... |
"nimi ale lon toki pona" is a song by YouTuber jan Misali which lists 137 common words in the constructed language Toki Pona. This challenge is not a duplicate of "How high can you count?" or "Alphabet printing challenge" because instead of numbers or single characters, it outputs random (to many programming languages)... |
We will say a string \$x\$ is cyclic maximal if there is no way to cycle its elements to get a lexicographically larger string. In other words there is no \$a\$ and \$b\$ such that \$a \oplus b = x\$ and \$b \oplus a > x\$, where \$\oplus\$ is concatenation.
For example [3,2,3,3] is not cyclic maximal because you can c... |
I recently found this game and have been enjoying it. Basically, there is a grid of colored tiles and you act by clicking on empty spaces. When you click an empty space, the first tile (if any) in each of the four axis-aligned directions is selected. If any color appears more than once, all tiles of that color are dest... |
Objective
Given an integer \$n\$ interpreted as two's complement binary, output two integers, namely the integer consisting of \$n\$'s bits at places of \$2^0, 2^2, 2^4, \cdots\$, and the integer consisting of \$n\$'s bits at places of \$2^1, 2^3, 2^5, \cdots\$.
Note that the input may be negative. Since \$n\$ is inter... |
The game is played on a 1x8 board with the following setup:
KNR..rnk
White's pieces are on the left, while black's pieces are on the right.
The king (K) can move 1 space in any direction.
The knight (N) can jump 2 spaces in any direction, regardless of bordering pieces.
The rook (R) can move any number of spaces in an... |
For the purpose of this challenge, arguments are things you pass to a function at the call site, while parameters are what the function uses in its implementation. Or, more succinctly: arguments = external, parameters = internal.
While there are several modern languages that have support for argument labels for func... |
Given a non-empty string containing only printable ASCII (codepoints 0x20 to 0x7E), write the shortest program or function that map the key to its value. Inside the string the key will always have a value and vice-versa.
How the key is made:
Start with an opening parenthesis (
Contains letters and/or numbers [a-zA-Z0-... |
The Rockstar programming language has "poetic number literals", allowing you to assign nonnegative, finite (at least one Rockstar interpreter supports infinity) numbers to variables without typing a single digit: just type words with length equal to each digit, modulo 10. For example,
This is a challenge
sets the vari... |
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