Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.
For example:
Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has only one digit, return it.
Follow up:
Could you do it without any loop/recursion in O(1) runtime?
class Solution(object):
def addDigits(self, num):
"""
:type num: int
:rtype: int
"""
if num == 0:
return 0
return int((num-1)%9 + 1)