看了N次Y总视频，终于过了😁😊

class MyQueue {
public:
    /** Initialize your data structure here. */
    stack<int> x1,y1;
    MyQueue() {

    }

    /** Push element x to the back of queue. */
    void push(int x) {
    x1.push(x);  
    }

    /** Removes the element from in front of queue and returns that element. */
    int pop() {
    while(x1.size()>1)y1.push(x1.top()),x1.pop();
    int s=x1.top();
    x1.pop();
    while(y1.size())x1.push(y1.top()),y1.pop();
    return s;
    }

    /** Get the front element. */
    int peek() {
    while(x1.size()>1)y1.push(x1.top()),x1.pop();
    int s=x1.top();
    while(y1.size())x1.push(y1.top()),y1.pop();
    return s;
    }

    /** Returns whether the queue is empty. */
    bool empty() {
    if(x1.size())  return false;
    return true;
    }
};

/**
 * Your MyQueue object will be instantiated and called as such:
 * MyQueue obj = MyQueue();
 * obj.push(x);
 * int param_2 = obj.pop();
 * int param_3 = obj.peek();
 * bool param_4 = obj.empty();
 */