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):
        self.stack1.append(node)

    def pop(self):
        while self.stack1:
            self.stack2.append(self.stack1.pop())
        node = self.stack2.pop()
        print(f'Pushed:{node}')
        while self.stack2:
            self.stack1.append(self.stack2.pop())
        return node

先全部放入stack1

然后从stack1全部放入stack2，即满足队列先进先出，从stack2中pop

再放回stack1则不改变顺序