Leetcode 155最小栈

155最小栈

class MinStack(object):

    def __init__(self):
        """
        initialize your data structure here.
        """
        self.items = []
        self.minitems = []


    def push(self, x):
        """
        :type x: int
        :rtype: None
        """
        if not self.minitems:
            self.minitems.append(x)
        elif self.minitems[-1] >= x:
            self.minitems.append(x)
        return self.items.append(x)


    def pop(self):
        """
        :rtype: None
        """
        if self.items[-1] == self.minitems[-1]:
            del self.minitems[-1]
        #if self.items == []:
        #    self.minitems.append(self.items[-1])
        return self.items.pop()


    def top(self):
        """
        :rtype: int
        """
        return self.items[-1]


    def getMin(self):
        """
        :rtype: int
        """
        return self.minitems[-1]