Sudoku is a simple game where the solver is given a 9×9 grid with 9 3×3 subgrids tiled in such a way as they are space filling, and non-overlapping. The object of the game is to fill the subgrids, every row, and every column with the numbers 1-9, inclusive, such that each number is used only once.

Every good Sudoku can be solved by using logic, mathematics, and guesswork. Bad Sudoku cannot be solved, because they have multiple solutions, an undesirable situation, or, even worse, no solution. There is currently no algorithm to determine if a given sudoku has no solution, the best that can be done is solve it until a logical contradiction is reached.

Sudoku are fun to solve, but they can be frustrating, especially ones that require the user to guess in order to solve it. To assist with this, I have found some sudoku solvers, and will be posting links to them. If you have such a solver, please do not hesitate to post it. Bonus points for odd, obscure, or old languages.

These are all C, C++, Java, or Python.

http://8325.org/sudoku/source.html

http://www.codeproject.com/KB/game/sudoku.aspx?fid=225854&df=90&mpp=25&noise=3&sort=Position&view=Quick&fr=26

http://sudokusecretcode.com/

http://www.sudoku-solver.net/index.php?solve=y&steps=complete&lang=English

http://www.colloquial.com/games/sudoku/java_sudoku.html

http://www.techfinesse.com/game/sudoku_solver.php

http://www.codeproject.com/KB/vb/sudoku.aspx?fid=242974&fr=13

This one is Haskell

http://haskell.org/haskellwiki/Sudoku#Monadic_Non-Deterministic_Solver