225. Implement Stack using Queues

 1 class MyStack {
 2     Queue<Integer> q = new LinkedList();
 3     // Push element x onto stack.
 4     public void push(int x) {
 5         for(int i = 0; i < q.size(); i++){
 6             q.offer(x);
 7             x = q.poll();
 8         }
 9         q.offer(x);
10     }
11 
12     // Removes the element on top of the stack.
13     public void pop() {
14         q.poll();
15     }
16 
17     // Get the top element.
18     public int top() {
19         return q.peek();
20     }
21 
22     // Return whether the stack is empty.
23     public boolean empty() {
24         return q.size() == 0;
25     }
26 }