Sudoku Solver Using Bit Arithmetic
UPDATE: Unfortunately this doesn't solve all sudokus yet. For example 300200000000107000706030500070009080900020004010800050009040301000702000000008006 proves to be too difficult for now. This will be fixed ASAP.
After 4 years of (mostly inactive) development, the solver can finally solve sudokus from each of WebSudoku.com's difficulty levels. Coming up next: lots of refactoring!