Recursive Digit Sum solution updated

[abhi887449]

Issue Number: #198

This submission closes #198 issue

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Hackerrank Problem Link:

https://www.hackerrank.com/challenges/recursive-digit-sum/problem

Submitted Hackerrank Solution Link:

C++ : https://www.hackerrank.com/challenges/recursive-digit-sum/submissions/code/293960349 Java : https://www.hackerrank.com/challenges/recursive-digit-sum/submissions/code/293965603 Python : https://www.hackerrank.com/challenges/recursive-digit-sum/submissions/code/293968217

Any other changes you made or something you would like to mention?