I’ve been doing a bit of work with Solver Foundation lately and as I got to know the package it suddenly occurred to me Solver Foundation could be easily used to solve Sudoku puzzles. While I knew that solving Sudoku in F# wasn’t particularly an original idea, Jon Harrop has a custom Sudoku solver in F# that dates back to 2007, but I thought using Solver Foundation might be an interesting approach. I was on the train at the time so I fired up VS and pretty quickly had a working solution. A little googling later revealed that I wasn’t at all the first to have thought of this, in fact there’s event a Sudoku example packaged with Solver Foundation, but using the OML solver language rather than F#. Anyway, as I have a working solution I thought I may as well show it here. At 121 lines, including comments, inputs and solution printing functions, I don’t think it’s too bad, however I do think there’s some room to make it even shorter.

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re: Solving Sudoku Puzzles using F# and Microsoft Solver Foundation - Frank de Groot - Schouten

At Microsoft PDC 2010, Bart de Smet demonstrated a LINQ provider that spews OML and invokes Solver Foundation, solving a Sudoku using LINQ in C#: http://bit.ly/bfzKCk. Unfortunately I haven't seen his code online anywhere.