| import java.util.ArrayList; |
| import java.util.List; |
| import java.util.NoSuchElementException; |
|
|
| |
| public class BoundedStack<T> { |
| private final List<T> items = new ArrayList<>(); |
| private final int capacity; |
|
|
| public BoundedStack(int capacity) { |
| if (capacity <= 0) { |
| throw new IllegalArgumentException("capacity must be positive"); |
| } |
| this.capacity = capacity; |
| } |
|
|
| public void push(T item) { |
| if (item == null) { |
| throw new NullPointerException("null items are not allowed"); |
| } |
| if (isFull()) { |
| throw new IllegalStateException("stack is full"); |
| } |
| items.add(item); |
| } |
|
|
| public T pop() { |
| if (isEmpty()) { |
| throw new NoSuchElementException("stack is empty"); |
| } |
| return items.remove(items.size() - 1); |
| } |
|
|
| public T peek() { |
| if (isEmpty()) { |
| throw new NoSuchElementException("stack is empty"); |
| } |
| return items.get(items.size() - 1); |
| } |
|
|
| |
| public List<T> top(int n) { |
| if (n < 0) { |
| throw new IllegalArgumentException("n must be >= 0"); |
| } |
| List<T> out = new ArrayList<>(); |
| for (int i = items.size() - 1; i >= 0 && out.size() < n; i--) { |
| out.add(items.get(i)); |
| } |
| return out; |
| } |
|
|
| public int size() { |
| return items.size(); |
| } |
|
|
| public boolean isEmpty() { |
| return items.isEmpty(); |
| } |
|
|
| public boolean isFull() { |
| return items.size() == capacity; |
| } |
|
|
| public int remaining() { |
| return capacity - items.size(); |
| } |
| } |
|
|
