QueueUsingStack

class MyQueue {
public:

    stack<int> s1;
    stack<int> s2;
    /** Initialize your data structure here. */
    MyQueue() {
        
    }
    
    /** Push element x to the back of queue. */
    void push(int x) {
        while(!s1.empty()) {
            s2.push(s1.top());
            s1.pop();
        }
        s2.push(x);
        while(!s2.empty()) {
            s1.push(s2.top());
            s2.pop();
        }
    }
    
    /** Removes the element from in front of queue and returns that element. */
    int pop() {
        int curr = s1.top();
        s1.pop();
        return curr;
    }
    
    /** Get the front element. */
    int peek() {
        return s1.top();
    }
    
    /** Returns whether the queue is empty. */
    bool empty() {
        return s1.empty();
    }
};