225. Implement Stack using Queues

Implement the following operations of a stack using queues.

push(x) – Push element x onto stack.
pop() – Removes the element on top of the stack.
top() – Get the top element.
empty() – Return whether the stack is empty.
Notes:
You must use only standard operations of a queue – which means only push to back, peek/pop from front, size, and is empty operations are valid.
Depending on your language, queue may not be supported natively. You may simulate a queue by using a list or deque (double-ended queue), as long as you use only standard operations of a queue.
You may assume that all operations are valid (for example, no pop or top operations will be called on an empty stack).

class MyStack {    Queue<Integer> queue1 = new LinkedList<Integer>();      Queue<Integer> queue2 = new LinkedList<Integer>();      Queue<Integer> q = new LinkedList<Integer>();      public void push(int x) {        queue1.offer(x);     }    public void pop() {        while(queue1.size()>1) queue2.offer(queue1.poll());          queue1.poll();          Queue<Integer> q = queue1;          queue1 = queue2;          queue2 = q;      }    public int top() {        while(queue1.size()>1) queue2.offer(queue1.poll());          int x = queue1.poll();          queue2.offer(x);          Queue<Integer> q = queue1;          queue1 = queue2;          queue2 = q;          return x;      }    public boolean empty() {        return queue1.isEmpty();     }}