''' 解题思路: 1、正常push没问题,直接用stackin.append() 2、pop()时,当stackout为空时,stackout.append(stackin.pop()),再调用stackout.pop()输出 注意:pop()之前,要确保不为空,用if stackin/stackout:判断 ''' # -*- coding:utf-8 -*- class Solution: def __init__(self): self.stackin = [] self.stackout = [] def push(self, node): # write code here self.stackin.append(node) def pop(self): # return xx if not self.stackout: while self.stackin: self.stackout.append(self.stackin.pop()) if self.stackout: return self.stackout.pop()