题解 | #包含min函数的栈#

# -*- coding:utf-8 -*-
class Solution:
    def __init__(self) -> None:
        self.s1=[]
        self.s2=[]
    def push(self, node):
        if not self.s2:
            self.s2.append(node) 
        self.s1.append(node)
        if len(self.s2)>0 and self.s2[-1]<=node:
            self.s2.append(self.s2[-1])
        if len(self.s2)>0 and self.s2[-1]>node:
            self.s2.append(node)
        # write code here
    def pop(self):
        self.s1.pop()
        self.s2.pop()
        # write code here
    def top(self):
        # write code herE
        if self.s1:
            return self.s1[-1]
        else:
            return None
    def min(self):
        if self.s2:
            return self.s2[-1]
        else:
            return None
        # write code here