leetcode--Implement Stack using Queues

mplement 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).

Update (2015-06-11):
The class name of the Java function had been updated to MyStack instead of Stack.

class MyStack {
    Queue<Integer> queue1 = new LinkedList<Integer>();
	Queue<Integer> queue2 = new LinkedList<Integer>();
	boolean turn = true;
	// Push element x onto stack.
    public void push(int x) {
        if(turn){
        	queue1.add(x);
        }else{
        	queue2.add(x);
        }
    }

    // Removes the element on top of the stack.
    public void pop() {
        if(turn){
        	while(queue1.size()>1){
        		queue2.add(queue1.poll());
        	}
        	queue1.poll();
        }else{
        	while(queue2.size()>1){
        		queue1.add(queue2.poll());
        	}
        	queue2.poll();
        }
        turn = !turn;
    }

    // Get the top element.
    public int top() {
    	if(turn){
        	while(queue1.size()>1){
        		queue2.add(queue1.poll());
        	}
        	return queue1.peek();
        }else{
        	while(queue2.size()>1){
        		queue1.add(queue2.poll());
        	}
        	return queue2.peek();
        }
    }

    // Return whether the stack is empty.
    public boolean empty() {
        return queue1.isEmpty()&&queue2.isEmpty();
    }
}