Here's my Python sudoku solver which I wrote about 10 years ago. http://petef.22web.org/sudoku/
It works by applying the solving techniques I came up with. No trial and error or backtracking is used, so it is not up to cracking the very hardest puzzles. Run time is 15 ms to 45 ms on a 2009 MacBook Pro using Python 2.7.9. There are verbose options to print the steps. Sizes and multiple grids are flexible. IIRC it took a day or two to adapt the program when the first samurai was published. $ python sudoku.py -i sudoku2.sud ***|7**|*** 1**|***|*** ***|43*|2** ---+---+--- ***|***|**6 ***|5*9|*** ***|***|418 ---+---+--- ***|*81|*** **2|***|*5* *4*|***|3** Solved, rating: dead easy Calculation took 18.006 ms 264|715|839 137|892|645 598|436|271 ---+---+--- 423|178|596 816|549|723 759|623|418 ---+---+--- 375|281|964 982|364|157 641|957|382 -- Pete Forman http://petef.22web.org/payg.html -- https://mail.python.org/mailman/listinfo/python-list
