LeetCode - 622 设计循环队列 （设计）

数组来实现队列

头指针指向当前头元素的上一个位置 尾指针指向尾元素

class MyCircularQueue {
    
    private int[] queue;//队列数组
    private int size;//队列中实际存放了多少元素
    private int head;//头指针
    private int tail;//尾指针
    private int capacity;//队列固定大小
    public MyCircularQueue(int k) {
    
        //队列固定大小为k
        this.queue = new int[k];
        this.size = 0;
        this.head = 0;
        this.tail = 0;
        this.capacity = k;

    }
    
    public boolean enQueue(int value) {
    
       if(isFull())//队列满了 值不能入队列
          return false;
        else{
    
            //将值放入队列尾部
            queue[tail] = value;
            //队列大小加一
            size += 1;
            //尾指针向后移动
            tail = (++tail) % this.capacity;
            return true;
        }
        
    }
    
    public boolean deQueue() {
    
        //如果队列为空 值出队列失败
       if(isEmpty())
          return false;
        else{
    
            //头指针向后移动
           head = (++head) % this.capacity;
           //队列大小减一
           size -= 1;
           return true;
        }
    }
    
    public int Front() {
    

        if(isEmpty())
          return -1;
        else 
          //返回头指针对应值
          return queue[head];
    }
    
    public int Rear() {
    
        if(isEmpty())
          return -1;
        else{
    
           // tail指向的是当前要存数的位置 所以队列中实际的最后一个数是tail的上一个位置
           int rear = (tail - 1 + this.capacity) % this.capacity;
           return queue[rear];
        }
    }
    
    public boolean isEmpty() {
    
        //判断队列的实际容量是否为0
       return this.size == 0;
    }
    
    public boolean isFull() {
    
        //判断队列中数的实际个数是否与队列容量相等
        return this.size == this.capacity;
    }
}

/** * 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(); */