Solutions for AdventOfCode (http://adventofcode.com/) as I learn Go.
(Original solutions in a variety of languages, perl, C, sh/awk/sed)
Each problem is devided into two parts but the second part of the problem is not known until the solution to the first part has been provided. This makes it difficult to know how to implement the first part.
Sometimes the first part can be extended for the second part, but many times a rewrite/refactor will be required. I don't guess correctly that often!