题解 | #求1+2+3+...+n#

为啥下面的不行？

# -*- coding:utf-8 -*-
class Solution:
    def Sum_Solution(self, n):
        # write code here
        result = (n+1)*n/2
        return result

这个就行？

# -*- coding:utf-8 -*-
class Solution:
    def Sum_Solution(self, n):
        # write code here
        result = int((n+1)*n/2)
        return result