Feat: Add Three sum in Math Section

[BamaCharanChhandogi]

Feature description

I think Two sum is available but the Three sum is not available.
I want to add three sum Problem.

Examples:

Input: array = [-1,0,1,2,-1,-4]
Output: [[-1,-1,2],[-1,0,1]]

[BamaCharanChhandogi]

@tianyizheng02 Could we work on this issue?

[tianyizheng02]

@BamaCharanChhandogi, read the contributing guidelines.

If you are interested in resolving an open issue, simply make a pull request with your proposed fix. We do not assign issues in this repo so please do not ask for permission to work on an issue.