On Sun, Aug 22, 2010 at 1:18 PM, Daniel Fischer <daniel.is.fisc...@web.de> wrote: > On Sunday 22 August 2010 20:12:16, Vladimir Matveev wrote: >> I think the problem is with terribly inefficient data representation. > > Worse, it's a terribly inefficient algorithm. > The constraints are applied too late, so a huge number of partial boards > are created only to be pruned afterwards. Since the ratio between obviously > invalid rows and potentially valid rows is large, the constraints should be > applied already during the construction of candidate rows to avoid > obviously dead branches.
I've written a sudoku solver myself, and IIRC I used lists. It always gave an answer within a second. So I believe Daniel has correctly identified the problem -- you need to prune earlier. Luke _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
