Python3 代码

from collections import deque

class MyQueue(object):

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


    def push(self, x):
        """
        Push element x to the back of queue.
        :type x: int
        :rtype: void
        """
        self.stack.append(x)


    def pop(self):
        """
        Removes the element from in front of queue and returns that element.
        :rtype: int       
        """
        if self.stack:
            return self.stack.popleft()
        else:
            return None


    def peek(self):
        """
        Get the front element.
        :rtype: int
        """
        if self.stack:
            return self.stack[0]
        else:
            return None


    def empty(self):
        """
        Returns whether the queue is empty.
        :rtype: bool
        """
        if self.stack:
            return len(self.stack) == 0 
        else:
            return True