力扣-225题 用队列实现栈（C++）

题目链接：https://leetcode-cn.com/problems/implement-stack-using-queues/
题目如下：

class MyStack {
public:
    //思路：一个队列在模拟栈弹出元素的时候只要将队列头部的元素（除了最后一个元素外） 重新添加到队列尾部
    queue<int> que;
    int count=0;
    /** Initialize your data structure here. */
    MyStack() {

    }
    
    /** Push element x onto stack. */
    void push(int x) {
        que.push(x);
        count++;
    }
    
    /** Removes the element on top of the stack and returns that element. */
    int pop() {
        for(int i=0;i<count-1;i++){
            que.push(que.front());
            que.pop();
        }

        int num=que.front();
        que.pop();
        count--;

        return num;
    }
    
    /** Get the top element. */
    int top() {
        for(int i=0;i<count-1;i++){
            que.push(que.front());
            que.pop();
        }

        int num=que.front();
        que.push(num);
        que.pop();

        return num;
    }
    
    /** Returns whether the stack is empty. */
    bool empty() {
        return que.empty();
    }
};

/**
 * Your MyStack object will be instantiated and called as such:
 * MyStack* obj = new MyStack();
 * obj->push(x);
 * int param_2 = obj->pop();
 * int param_3 = obj->top();
 * bool param_4 = obj->empty();
 */