基于数组实现循环队列 Implementation of Circular Queue Based on Static Array

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题目来源：https://leetcode.com/explore/learn/card/queue-stack/228/first-in-first-out-data-structure/1337/

class MyCircularQueue {

    int[] circularQueue = null;
    int headPos, rearPos = -1, amount;
    /** Initialize your data structure here. Set the size of the queue to be k. */
    public MyCircularQueue(int k) {
        circularQueue = new int[k];
    }

    /** Insert an element into the circular queue. Return true if the operation is successful. */
    public boolean enQueue(int value) {
        if (isFull()) return false;
        if (rearPos < circularQueue.length-1) rearPos++;
        else rearPos = (rearPos+1) % circularQueue.length;
        circularQueue[rearPos] = value;
        amount++;
        return true;
    }

    /** Delete an element from the circular queue. Return true if the operation is successful. */
    public boolean deQueue() {
        if (isEmpty()) return false;
        headPos = ++headPos % circularQueue.length;
        amount--;
        return true;
    }

    /** Get the front item from the queue. */
    public int Front() {
        if (isEmpty()) return -1;
        return circularQueue[headPos];
    }

    /** Get the last item from the queue. */
    public int Rear() {
        if (isEmpty()) return -1;
        return circularQueue[rearPos];
    }

    /** Checks whether the circular queue is empty or not. */
    public boolean isEmpty() {
        return amount == 0;
    }

    /** Checks whether the circular queue is full or not. */
    public boolean isFull() {
        return amount == circularQueue.length;
    }
}

/**
 * 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();
 */