设计具有取最小值的栈python实现

class stack1(object):
    def __init__(self):
        self.stackData = []
        self.stackMin = []

    def push(self,item):
        self.stackData.append(item)
        if not self.stackMin:
            self.stackMin.append(item)
        else:
            self.stackMin.append(min(self.stackMin[-1],item))
        return self.stackData,self.stackMin

    def pop(self):
        if not self.stackData:
            raise Exception('stack is empty')
        return self.stackData.pop(),self.stackMin.pop()


    def GetMin(self):
        if not self.stackMin:
            raise Exception('stack is empty')
        return self.stackMin[-1]


a = stack1()
a.push(6)
a.push(4)
a.push(2)
a.push(7)
a.push(1)
b,c = a.push(9)
print(b,c)
d,e = a.pop()
print(b,c)
print(d,e)
m = a.GetMin()
print(m)
           

用两个数组

O（1）时间