258. Add Digits | Leetcode solution

258. Add Digits

 Given an integer num, repeatedly add all its digits until the result has only one digit, and return it.

 

Example 1:

Input: num = 38
Output: 2
Explanation: The process is
38 --> 3 + 8 --> 11
11 --> 1 + 1 --> 2 
Since 2 has only one digit, return it.

Example 2:

Input: num = 0
Output: 0

 

Constraints:

• 0 <= num <= 231 - 1

solution:

class Solution {

public:

    int addDigits(int num) {

         int n = num;

         if(num == 10)

             return 1;

        if(num /10 == 0)

            return num;

        while(n /10 != 0 )

        {

            int a = n %10;

            n = n /10;

            int b = n %10;

            n = n/10;

            n = n+a+b;

        }

        return n ;

    }

};