Add solutions to InterviewBit problems.

[LeCeee]

I am not sure if it fits competitive programming,but interview bit has some good questions that could be included in this repo. @rathoresrikant

[rathoresrikant]

Yeah, I agree with you. Thanks for raising this issue.

[LeCeee]

I'll add the solutions too.

[rrishabh145]

Folder containing InterviewBit solution added. Please accept the Pull request.

[rathoresrikant]

Accepted and merged. Thanks.