225.用队列实现栈

难度：简单
题目描述：

思路总结：又是一道瞎写的题，不知道再考查什么。。。
题解一：

from collections import deque

class MyStack:

    def __init__(self):
        """
        Initialize your data structure here.
        """
        self.queue = deque()
        self.helper = deque()

    def push(self, x: int) -> None:
        """
        Push element x onto stack.
        """
        self.queue.append(x)

    def pop(self) -> int:
        """
        Removes the element on top of the stack and returns that element.
        """
        for i in range(len(self.queue)-1):
            self.helper.append(self.queue.popleft())
        res = self.queue.popleft()
        while self.helper:
            self.queue.append(self.helper.popleft())
        return res

    def top(self) -> int:
        """
        Get the top element.
        """
        front = -1
        while self.queue:
            front = self.queue.popleft()
            self.helper.append(front)
        while self.helper:
            self.queue.append(self.helper.popleft())
        return front

    def empty(self) -> bool:
        """
        Returns whether the stack is empty.
        """
        return len(self.queue) == 0
# Your MyStack object will be instantiated and called as such:
# obj = MyStack()
# obj.push(x)
# param_2 = obj.pop()
# param_3 = obj.top()
# param_4 = obj.empty()

题解一结果：