设计循环双端队列

/*
 * This solution implements the MyCircularDeque class using an array to represent the deque.
 * The key is to maintain two pointers, front and rear, to track the positions where elements
 * are inserted or removed. We also keep track of the number of elements in the deque to check
 * for full and empty conditions.
 * Note: Java Streams are not particularly suitable for this problem, as it involves direct manipulation
 * of array indices and maintaining state, which is more straightforward with traditional loops and conditions.
 */

import java.util.stream.IntStream;

public class MyCircularDeque {
    private int[] deque;
    private int front;
    private int rear;
    private int size;
    private int capacity;

    public MyCircularDeque(int k) {
        capacity = k;
        deque = new int[k];
        front = 0;
        rear = -1;
        size = 0;
    }

    public boolean insertFront(int value) {
        if (isFull()) return false;
        front = (front - 1 + capacity) % capacity;
        deque[front] = value;
        size++;
        if (size == 1) rear = front;
        return true;
    }

    public boolean insertLast(int value) {
        if (isFull()) return false;
        rear = (rear + 1) % capacity;
        deque[rear] = value;
        size++;
        return true;
    }

    public boolean deleteFront() {
        if (isEmpty()) return false;
        front = (front + 1) % capacity;
        size--;
        return true;
    }

    public boolean deleteLast() {
        if (isEmpty()) return false;
        rear = (rear - 1 + capacity) % capacity;
        size--;
        return true;
    }

    public int getFront() {
        if (isEmpty()) return -1;
        return deque[front];
    }

    public int getRear() {
        if (isEmpty()) return -1;
        return deque[rear];
    }

    public boolean isEmpty() {
        return size == 0;
    }

    public boolean isFull() {
        return size == capacity;
    }
}