This subject is one I struggle with quite a lot. I have only gotten better by solving problems related to "combinations" and "permutations", learning the patterns and techniques and searching around the web.

I feel it would help a lot (specially to people that are just starting) if we added an "n choose k" section to Explore/Learn, where the math of combinatorics is explained, next to coding techniques, patterns and sample problems.

Just like there are other sections on recursion, binary search, etc...

Thanks to all Leetcoders and the Leetcode team for all the great work you do!!