FloodIt Solver
Ever since I dicovered FloodIt (or Pixlated) on my old BlackBerry Bold 9900, I would wonder if every one of the provided puzzles could actually be solved within the alloted 21 moves.
I first attempted to solve this problem in highschool and did not get further than just making a playable version of the game.
Later, in my first year of university, I made another playable version and implemented a greedy algorithm with mediocre results.
Finally, in my third year of university, I was able to take part in a course that would provide me with the means to actually find the optimal solution to an arbitrary FloodIt board.
As far as I'm aware, we are the first people to successfully use search algorithms to optimally solve this issue.
Please see our final paper here
A good reference paper: http://arxiv.org/pdf/1001.4420v3.pdf