leetcode-easy-design-155 Min Stack

mycode   21.48%

class MinStack(object):

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

    def push(self, x):
        """
        :type x: int
        :rtype: None
        """
        self.res.append(x)
        

    def pop(self):
        """
        :rtype: None
        """
        if not self.res:
            return None
        else:
            val = self.res[-1]
            self.res[:] = self.res[:-1]
            return val
        

    def top(self):
        """
        :rtype: int
        """
        if not self.res:
            return None
        else:
            return self.res[-1]
      
        

    def getMin(self):
        """
        :rtype: int
        """
        if not self.res:
            return None
        else:
            return min(self.res)
      
        


# Your MinStack object will be instantiated and called as such:
# obj = MinStack()
# obj.push(x)
# obj.pop()
# param_3 = obj.top()
# param_4 = obj.getMin()

列表是有pop操作的

  self.res.pop()

参考

始终更新最小值，所以节省 了时间

class MinStack(object):

    def __init__(self):
        """
        initialize your data structure here.
        """
        self.stack = []
        self.minval = 99999999999999999

    def push(self, x):
        """
        :type x: int
        :rtype: None
        """
        if(x < self.minval):
            self.minval = x
        self.stack.append(x)

    def pop(self):
        """
        :rtype: None
        """
        if(self.stack[-1] == self.minval):
            self.minval = 99999999999
            for num in self.stack[0:-1]:
                if(num < self.minval):
                    self.minval = num
        self.stack.pop(-1)

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

    def getMin(self):
        """
        :rtype: int
        """
        return self.minval


# Your MinStack object will be instantiated and called as such:
# obj = MinStack()
# obj.push(x)
# obj.pop()
# param_3 = obj.top()
# param_4 = obj.getMin()