https://projecteuler.net/ is a website with various coding challenges.
I have just found out about this website and have begun coming up with solutions. My solutions are in no way optimal.
If I get past the first 100 questions the new answers will be in a private repository, Project Euler requests that nobody publish answers to questions outside of the first 100.
I may come back through and attempt to further optimize or document my solutions, but the forums on project euler offer a great place for that.