Update: Added Unary Operator in SumOfDigits algorithm

[chetannada]

Update: I have Added Unary Operator (+) in SumOfDigits algorithm, It's Optimized Solution in current tech stack.
If there is any thing need to update in this PR , I'll update it.
Thanks.

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Describe your change:

• Add an algorithm?
• Fix a bug or typo in an existing algorithm?
• Documentation change?

Checklist:

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