Sudoku

Sudoku animation in SWI Prolog

Prolog code: sudoku.pl

Sample PostScript file, a self-contained saved animation for a Sudoku puzzle (open it with "gv" or "gs" to view it): solved.ps.gz

You need SWI-Prolog > 5.10 (recommended: latest git version). Start it with

      swipl -f sudoku.pl

You also need to have the PostScript viewer "gs" installed.

Here are a few example queries that you can try:


      ?- problem(1, Rows), show([], Rows).

      ?- problem(3, Rows), show([ff], Rows).

      ?- show([], Rows).

The first argument is a list of labeling options as described in SWI-Prolog's CLP(FD) library documentation. The second argument is a list of 9 rows that are to be completed to a Sudoku Latin square. Each row is a list of 9 variables, which can also be already instantiated to integers to fill in initial elements. The predicate can be used in all directions: You can complete partial squares, test complete squares, and enumerate all possible Sudoku Latin squares. As a side-effect, you see an animation of the constraint solving process. A few sample puzzles are included.

Here's an intermediate state:

And here is a picture of a finished animation:

Further reading: Neumerkel at al., Visualizing Solutions with Viewers.

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