I made a sudoku solver back when I was in school. It's quite simple and almost a textbook case for backtracking. Even brute-force algorithms are instantaneous on the hardest puzzles.

I'm still mesmerized by the 15-line prolog sudoku solver: http://programmablelife.blogspot.com/2012/07/adventures-in-d...

It's just using a library, you can get the same effect in any language with a constraint satisfaction library.

Completely agree here, the entire 'solver' is a library there.

However, it does show how cool and versatile SAT solvers are for people who haven't used or seen them yet.