LeetCode || Implement Queue using Stacks

class Queue {public:    // Push element x to the back of queue.    void push(int x) {        s1.push(x);    }    // Removes the element from in front of queue.    void pop(void) {        if(s2.size() == 0)        {            while(s1.size()!=0)            {                s2.push(s1.top());                s1.pop();            }        }        s2.pop();    }    // Get the front element.    int peek(void) {        if(s2.size() == 0)        {            while(s1.size()!=0)            {                s2.push(s1.top());                s1.pop();            }        }        return s2.top();    }    // Return whether the queue is empty.    bool empty(void) {        if(s1.size() == 0 && s2.size() == 0)            return true;        return false;    }        stack<int> s1;    stack<int> s2;};