During one week of Dev Bootcamp, I became obsessed with the idea that I could make a faster solution to the sudoku challenge. I made a couple solutions, this is my fastest one. This is insane, because it isn't what ruby is for, but here it is anyway.
To run the original 15 puzzles, just run
ruby runner.rb. Modify the range in runner if you want to run the 16th puzzle ('the hardest puzzle' by some finnish mathematician) or a different combination of puzzles. The solved strings will print to the terminal and a benchmark will also print.
The current runtime for the 15 puzzles.