2017.08.25阿里笔试题

from math import sqrt

class Solution(object):
    def num(self, k):
        x = int(sqrt(2*k))
        prenum = x * (x-1) / 2
        result = k - prenum
        return int(result)
if __name__ == '__main__':
    s  = Solution()  print(s.num(10))