Java program for Adding Digits

Question

Given num = 38, the process is like: 3 + 8 = 11, 1 + 1 = 2. Since 2 has only one digit, return it. but my function returns 11 ? what is wrong with my logic? Help !!

public class Solution {
    public int addDigits(int num) {
    int result=doSum(num);
    return result;
    }

    public static int doSum(int num){
        int sum=0,digit;
        while(num!=0){
            digit=num%10;
            sum+=digit;
            num=num/10;
        }
        if(sum/10!=0){
            doSum(sum);
        }
        return sum;
    }
}

Show your main function also.

Manwal
– Manwal

2015-09-22 07:34:03 +00:00
Commented Sep 22, 2015 at 7:34 — Manwal
– Manwal, Commented Sep 22, 2015 at 7:34
you need to say return doSum(sum);

SomeJavaGuy
– SomeJavaGuy

2015-09-22 07:34:04 +00:00
Commented Sep 22, 2015 at 7:34 — SomeJavaGuy
– SomeJavaGuy, Commented Sep 22, 2015 at 7:34

Madhawa Priyashantha · Accepted Answer · 2015-09-22 07:35:11Z

5

if(sum/10!=0){
    doSum(sum);
}

This is what is wrong with your logic. You recursively call doSum() on the new sum but you do nothing with the result. So you need to change this to:

if(sum/10!=0){
   sum = doSum(sum);
}

edited Sep 22, 2015 at 7:35

Madhawa Priyashantha

9,9057 gold badges38 silver badges65 bronze badges

answered Sep 22, 2015 at 7:34

Amr

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