题目：

题解：

class MyStack {Queue<Integer> queue;/** Initialize your data structure here. */public MyStack() {queue = new LinkedList<Integer>();}/** Push element x onto stack. */public void push(int x) {int n = queue.size();queue.offer(x);for (int i = 0; i < n; i++) {queue.offer(queue.poll());}}/** Removes the element on top of the stack and returns that element. */public int pop() {return queue.poll();}/** Get the top element. */public int top() {return queue.peek();}/** Returns whether the stack is empty. */public boolean empty() {return queue.isEmpty();}
}