addDigits

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Given a non-negative integer num, repeatedly add all its digits until the result has only one digit.

Example:

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



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class Solution {
public:
	int addDigits(int num) {
		string s;
		s= to_string(num);
		if(num<10){
            return num;
        }
		int tm = 0;
		while (1) {
			for (int i = 0; i < s.size(); i++) {
				tm = tm+ (s[i] - '0') + (s[s.size() - 1 - i] - '0') ;
				

			}
			tm = tm / 2;
			if (tm < 10 && tm != 0) {
				break;
			}
			s = to_string(tm);
			tm = 0;
			
		}
		return tm;
	}
};