[redcodenl]

I wonder how much of that is programmed/automated and how much work is still being done manually...

Backtracking and eliminating numbers can be easily automated.

[Fiahil]

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.

[ben-schaaf]

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

[conistonwater]

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

[redcodenl]

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.

[bmn__]

https://old.reddit.com/r/programming/comments/1awnv/solving_...