class Solution(object):
def addDigits(self, num):
"""
:type num: int
:rtype: int
"""
while num % 10 != num:
s = str(num)
num = sum([int(x) for x in s])
return num
class Solution(object): #具有周期性
def addDigits(self, num):
if num == 0:
return 0
if num%9 == 0:
return 9
return num%9