myQueue.cpp

class MyQueue {
public:
    MyQueue() {
    }

    void push(int x) {
        s1.push(x);
    }

    int pop() {
        if (!s2.empty()) {
            int ret = s2.top();
            s2.pop();
            return ret;
        }
        move();
        return pop();
    }

    int peek() {
        if (!s2.empty())
            return s2.top();
        move();
        return s2.top();
    }

    bool empty() {
        return s1.empty() && s2.empty();
    }

    void move() {
        while(!s1.empty()) {
            int temp = s1.top();
            s1.pop();
            s2.push(temp);
        }
    }
private:
    stack<int> s1, s2;
};

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