50 Project Euler solutions (http://projecteuler.net/problems)! CodeEval (https://www.codeeval.com/open_challenges/) and algorithm problems. See /euler, /codeeval, and /algo directories. Please do NOT see my solution for a problem unless you have first tried it yourself. (Also, see my repo on RubyQuiz, CodeWars, InterviewCake, and other challenge questions. Plus see my Test-First Ruby and App Academy solutions.)