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.

public class Solution {   public int getAllSum(int val) {		int sum = 0;		while (val > 0) {			sum += val % 10;			val /= 10;		}		return sum;	}		public  int addDigits(int num) {		if (num <= 0) 			return 0;		while (num >= 10) {			num = getAllSum(num);		}		return num;	}}