Hoffa online sudoku solver

hoffa.se

Please enter your Sudoku.
All characters except 1..9 are interpreted as an unknown cell.
F.i. use 0 as unknown and you can easily use the numeric keypad to enter your Sudoku.
Autotab is enabled.




Solve a preselected sudoku

sudoku_unsolved_easy1
sudoku_unsolved_extra_hard1
sudoku_unsolved_extra_hard2
sudoku_unsolved_extra_hard3
sudoku_unsolved_extra_hard4
sudoku_unsolved_extra_hard5
sudoku_unsolved_extra_hard6
sudoku_unsolved_hard1
sudoku_unsolved_hard2
sudoku_unsolved_hard3
sudoku_unsolved_hard4
sudoku_unsolved_medium1

About the algorithm

An easy soduko will be solved in < 30ms
An extra har soduko will be solved in about 30ms - 200ms depending on complexity

The algorithm first uses a "slice and dice" break attempt.
If the sudoku still is not solved it tries with an "extreme elimination" attempt.
If still not solved, the algorithm finds the 50% guessing cells and runs a matrix of
four of them. (16 guesses). In some cases less then four 50% guessing cells are found.
Then the matrix of course will be smaller.

About the author

More information about the author can be found here: hoffa.se (in swedish)