循环队列简单实现

leetcode 622. 设计循环队列

class MyCircularQueue {
    private int[] queue;
    private int head;
    private int tail;
    private boolean isEmpty;

    public MyCircularQueue(int k) {
        queue = new int[k];
        head = 0;
        tail = 0;
        isEmpty = true;
    }
    
    /**
     * 1、若为满，则返回false
     * 2、将tail设置为value，将tail往右移动
     * 3、判断tail是否超过数组长度，若超过则将tail设置为0
     * 4、enQueue成功时，需要将isEmpty属性修改为false
     */
    public boolean enQueue(int value) {
        if (isFull()) {
            return false;
        }
        queue[tail] = value;
        tail++;
        if (tail == queue.length) {
            tail = 0;
        }
        isEmpty = false;
        return true;
    }
    
    /**
     * 1、若为空，则返回false
     * 2、获取head位置的值，将head往右移动
     * 3、若head超过数组长度，则将head设置为0
     * 4、判断head和tail是否重合，若重合则说明队列为空，修改isEmpty属性
     */
    public boolean deQueue() {
        if (isEmpty()) {
            return false;
        }
        int v = queue[head];
        head++;
        if (head == queue.length) {
            head = 0;
        }
        if (head == tail) {
            isEmpty = true;
        }
        return true;
    }
    
    public int Front() {
        if (isEmpty()) {
            return -1;
        }
        return queue[head];
    }
    
    public int Rear() {
        if (isEmpty()) {
            return -1;
        }
        if (tail == 0) {
            return queue[queue.length - 1];
        }else {
            return queue[tail - 1];
        }
    }
    
    public boolean isEmpty() {
        return isEmpty;
    }
    
    public boolean isFull() {
        // 头和尾重合，并且队列不为空，则为full
        return head == tail && (!isEmpty);
    }
}

/**
 * Your MyCircularQueue object will be instantiated and called as such:
 * MyCircularQueue obj = new MyCircularQueue(k);
 * boolean param_1 = obj.enQueue(value);
 * boolean param_2 = obj.deQueue();
 * int param_3 = obj.Front();
 * int param_4 = obj.Rear();
 * boolean param_5 = obj.isEmpty();
 * boolean param_6 = obj.isFull();
 */