Sudoku Solver in python (codingismycraft.com)

In my opinion the most impressive sudoku solver in Python is the one using Z3: http://rise4fun.com/Z3Py/tutorialcontent/guide#h210

Less than 30 lines of code just specifying what is a Sudoku game is!

The code is missing one of the "groups". There should be 27 (one for each of the 9 rows, columns and 3x3 squares), but there are only 26. The missing one is the column [8 ... 80].

Probably the most famous Sudoku program is Peter Norvig's, also written in Python:

http://www.norvig.com/sudoku.html

A few years ago I wrote a sudoku solver using the Knuth Dancing Limks algorithm. It's kind of a fun project, and I included an option to output the board as it recurses.

http://cavernum.net/dlsudoku/