【Leetcode】Add Digits(easy)

Question

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?

Code

#include<iostream>using namespace std;class Solution {public:    int addDigits(int num) {        while (num>=10) {            num = num/10 + num % 10;        }        return num;    }};int main() {    Solution so;    int num = 38;    cout<<so.addDigits(num)<<endl;    system("pause");    return 0;}