I did this once! I was given a "create Battleship" take-home assignment. Normally, I'd say, "yeah, I don't have time for this". But I happen to really like that game and had never thought of how to model it in code. So I took up the challenge. I spent time whiteboarding classes, interfaces, writing tests... in the end, I had a solid solution. I submitted my code and as I was doing so, I thought, "you know, this really could be handled by a couple of Set data structures. After hitting send, I did a quick follow-up with, "you know, this has a very simple solution" and typed some example code right in the body of the email. I love it when I can't just leave a problem alone. The hiring manager appreciated it too!
Isn't it fun when you can take a game you play and write an implementation (both the game and the solver), thinking through all the details, and at the end, the solution is simple, elegant, and enlightening?
For many years I played Peg Solitaire, and after reading Norvig's AI:AMA, realized that Peg Solitaire was a fairly easy game to write a solver for. It wasn't that hard to write, but it turns out that I've only ever implemented recursion using function calls to implement a stack, rather than the iterative equivalent (using a python list as a stack, and a Set to save previously visited boards). Having the confidence of the working recursive version, and then reading up on iterative implementations, i was finally able to get a working iterative version (for some reason it's really unnatural-feeling to me) working.
