Add Digits

[theumeshshelke]

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

Follow up: Could you do it without any loop/recursion in O(1) runtime?

[theumeshshelke]

class Solution { public: int addDigits(int num) { while(num>9){ int ans=0,rem; while(num!=0){ rem=num%10; num=num/10; ans=ans+rem; } num=ans; } return num; } };