题解 | #用两个栈实现队列#

# -*- coding:utf-8 -*-
class Solution:
    def __init__(self):
        self.stack1 = []
        self.stack2 = []
    def push(self, node):
        # write code here
        self.stack1.append(node)

    def pop(self):
        # return xx
        while self.stack1:
            x=self.stack1.pop()
            self.stack2.append(x)
        x=self.stack2.pop()
        while self.stack2:
            y=self.stack2.pop()
            self.stack1.append(y)
        return x