On December 8, 2019 I competited at ACM ICPC Kharagpur Regionals 2019-20. My team was able to solve only 2 problems. Except those we were at the end to finish more 3 problems. But as we weren't able to optimise a formula of Combination (in the Chef and Diamond problem) and some other implementation problems(for other 2 problems) we weren't able to solve any of three.Can anyone guide me from where and how can I prepare for having a good command on mathematics for programming. Also mention some good sites or books to prepare.