package math;

/**
 * Created by gouthamvidyapradhan on 02/08/2017.
 * 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?

 */
public class AddDigits {

    public static void main(String[] args) throws Exception{
        System.out.println(new AddDigits().addDigits(38));
    }

    public int addDigits(int num) {
        if(num == 0) return 0;
        return num % 9 == 0 ? 9 : num % 9;
    }

}