Q225MyStack.java

import java.util.LinkedList;
import java.util.Queue;


/*
Description:
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).

 * 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();
 * boolean param_4 = obj.empty();
 
*/

public class Q225MyStack {
    Queue<Integer> queue;
    
    public Q225MyStack() {
        queue = new LinkedList<>();
    }

    public void push(int x) {
        queue.add(x);
        for(int i = 1; i < queue.size(); i++){
            queue.add(queue.remove());
        }
    }

    public int pop() {
        return queue.remove();
    }

    public int top() {
        return queue.peek();
    }

    public boolean empty() {
        return queue.isEmpty();
    }
}