Codechef: Add solution to the MINIMAX Problem

[HarshCasper]

This is a(n):

• [X] New algorithm
• [ ] Update to an existing algorithm
• [ ] Error
• [X] Proposal to the Repository

Details:

MINIMAX is a problem available on Codechef. My proposal is to add the solution for this problem.

[HarshCasper]

I would be highly obliged if you can assign me this issues @AdiChat @arnavb