我的算法之路44--包含min函数的栈

class Solution:
    def __init__(self):
        self.stack=[]
        self.minstack=[]
    def push(self, node):
        # write code here
        self.stack.append(node)
        if not self.minstack or (self.minstack and self.minstack[-1]>node):
            self.minstack.append(node)
        else:
            self.minstack.append(self.minstack[-1])
    def pop(self):
        # write code here
        self.minstack.pop()
        return self.stack.pop()
    def top(self):
        # write code here
        return self.stack[-1]
    def min(self):
        # write code here
        return self.minstack[-1]