1 public class Solution {
 2     /**
 3      * @param num a non-negative integer
 4      * @return one digit
 5      */
 6     public int addDigits(int num) {
 7         // Write your code here
 8         while(num / 10 > 0){
 9             int[] tmp = getNum(num);
10             num = 0;
11             for(int i=0; i<tmp.length; i++){
12                 num = num + tmp[i];
13             }
14         }
15        return num;
16     }
17 
18     private int[] getNum(int num){
19         int length = Integer.toString(num).length();
20         int[] tmp = new int[length];
21         int i = 0;
22         while (num / 10 > 0){
23 
24             tmp[i] = num % 10;
25             num = num / 10 ;
26             i++;
27         }
28         tmp[length-1] = num;
29         return tmp;
30     }
31    
32 }