sumDigits challenge

Hi,

http://codingbat.com/prob/p163932

I am working on above challenge
Given a non-negative int n, return the sum of its digits recursively (no loops). Note that mod (%) by 10 yields the rightmost digit (126 % 10 is 6), while divide (/) by 10 removes the rightmost digit (126 / 10 is 12).

sumDigits(126) → 9
sumDigits(49) → 13
sumDigits(12) → 3

i was not sure how to find the sum of digits recursively without loop which i worked earlier. please advise
LVL 7
gudii9Asked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

d-glitchCommented:
Do you remember how to break up an integer into the LAST digit and the REST using % and / .

Recursion works by letting a function call itself multiple times, each time with a smaller or simpler argument.

The pseudo code would be something like:
function sumDigits( n)
sum = 0
if arg = 0 
     return sum
else
     sum = sum + LAST( arg) + sumDigits( REST( arg))

Open in new window


RECURSION is probably the single most important and elegant topic in computer science.
You should really read up on it if you don't understand the concept.  Challenges are not going to be enough.
0
gudii9Author Commented:
Do you remember how to break up an integer into the LAST digit and the REST using % and / .
yes
RECURSION is probably the single most important and elegant topic in computer science.
You should really read up on it if you don't understand the concept.  Challenges are not going to be enough.
where should i read up on it? Any best material,book, site?
0
d-glitchCommented:
Here are a couple of references:
     http://introcs.cs.princeton.edu/java/23recursion/
     http://arxiv.org/pdf/cs/9301113


My pseudo code needs some mods:
function sumDigits( n)
if n = 1   
     return 1
else   
     return  LAST + sumDigits( REST)

Open in new window

0

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Ultimate Tool Kit for Technology Solution Provider

Broken down into practical pointers and step-by-step instructions, the IT Service Excellence Tool Kit delivers expert advice for technology solution providers. Get your free copy now.

rrzCommented:
My pseudo code is a little different from d-glitch
if input is 0 then return 0
if not then return last + sumDigits(rest)
0
gudii9Author Commented:
I will try
0
gudii9Author Commented:
public int sumDigits(int n) {
  if (n < 10) 
{return n;
}
  return (n % 10) + sumDigits(n/10);
}

Open in new window


above passes all test. any improvements or alternate approaches?
0
rrzCommented:
 if (n < 10)
{return n;
Brilliant! I like your base case much better.
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Java

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.