力扣：622. 设计循环队列-优快云博客

这篇博客介绍了如何使用Java实现循环队列，包括基于数组和链表的两种实现方式。作者提供了详细的代码实现，包括入队、出队、获取队头和队尾元素以及检查队列是否为空或已满的方法。示例展示了在数据结构中如何高效地管理数据队列。

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/**
 * @author xnl
 * @Description:
 * @date: 2022/8/2   21:35
 */
public class Solution {

}

// s使用数组
class MyCircularQueue {
    private int front;
    private int rear;
    private int capacity;
    private int[] elements;

    public MyCircularQueue(int k) {
        capacity = k + 1;
        elements = new int[capacity];
        rear = front = 0;
    }

    /**
     * 入队
     * @param value
     * @return
     */
    public boolean enQueue(int value) {
        if (isFull()){
            return false;
        }
        elements[rear] = value;
        rear = (rear + 1) % capacity;
        return true;
    }

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

    public int Front() {
        if (isEmpty()){
            return  -1;
        }
        return elements[front];
    }

    public int Rear() {
        if (isEmpty()){
            return  -1;
        }
        return elements[(rear - 1 + capacity) % capacity];
    }

    public boolean isEmpty() {
        return rear == front;
    }

    public boolean isFull() {
        return ((rear + 1) % capacity) == front;
    }
}

// 使用链表
class MyCircularQueue2 {
    ListNode head;
    ListNode tail;
    int size;
    int capacity;

    public MyCircularQueue2(int k) {
        capacity = k;
        size = 0;
    }

    /**
     * 入队
     * @param value
     * @return
     */
    public boolean enQueue(int value) {
        if (isFull()){
            return false;
        }
        ListNode node = new ListNode(value);
        if (head == null){
            head = tail = node;
        } else {
            tail.next = node;
            tail = node;
        }
        size++;
        return true;
    }

    public boolean deQueue() {
        if (isEmpty()){
            return false;
        }
        head = head.next;
        size--;
        return true;
    }

    public int Front() {
        if (isEmpty()){
            return  -1;
        }
        return head.value;
    }

    public int Rear() {
        if (isEmpty()){
            return -1;
        }
        return tail.value;
    }

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

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

    class ListNode{
        int value;
        ListNode next;

        public ListNode(int value){
            this.value = value;
        }
    }
}