225 - Implement Stack Using Queues

#easy

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.

class MyStack {
public:
    queue<int> queue1;
    MyStack() {
        
    }
    
    void push(int x) {
        queue1.push(x);
    }
    
    int pop() {
        int pop_pos = queue1.size();
        int move_int;
        while ( pop_pos > 0 ) {
            move_int = queue1.front();
            queue1.pop();
            pop_pos--;
            if ( pop_pos > 0 ) queue1.push(move_int);
        }

        return move_int;
    }
    
    int top() {
        return queue1.back();
    }
    
    bool empty() {
        return ( queue1.empty() );
    }
};

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