LC-(E)- Implement Stack using Queues.cpp

// Implement a last-in-first-out (LIFO) stack using only two queues. The implemented stack should support all the functions of a normal stack (push, top, pop, and empty).

// Implement the MyStack class:

// void push(int x) Pushes element x to the top of the stack.
// int pop() Removes the element on the top of the stack and returns it.
// int top() Returns the element on the top of the stack.
// boolean empty() Returns true if the stack is empty, false otherwise.
// Notes:

// You must use only standard operations of a queue, which means that only push to back, peek/pop from front, size and is empty operations are valid.
// Depending on your language, the queue may not be supported natively. 
// You may simulate a queue using a list or deque (double-ended queue) as long as you use only a queue's standard operations.


class MyStack {
public:

    queue<int> q2;
    queue<int> q1;

    MyStack() {
        queue<int> q2;
        queue<int> q1;
    }
    
    void push(int x) {
        q1.push(x);
    }
    
    int pop() {
        while(q1.size()!=1){
            q2.push(q1.front());
            q1.pop();
        }
        int x= q1.front();
        q1.pop();

        while(!q2.empty()){
            q1.push(q2.front());
            q2.pop();
        }

        return x;
    }
    
    int top() {

        while(q1.size()!=1){
            q2.push(q1.front());
            q1.pop();
        }

        int x =q1.front();
        q1.pop();

        q2.push(x);
        

        while(!q2.empty()){
            q1.push(q2.front());
            q2.pop();
        }

        return x;

    }
    
    bool empty() {

        return q1.empty();
        
    }
};