leetcode Add Digits

原题链接：https://leetcode.com/problems/add-digits/

Description

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.

class Solution {
public:
int addDigits(int num) {
while (num >= 10) {
int ret = 0;
do ret += num % 10; while (num /= 10);
num = ret;
}
return num;
}
};