su-doku questions...?

spurred on by occular's post, i decided to try and write my own deterministic sudoku solver. at the moment i'm using java, but i think that prolog or any other AI language would be ideal. anyway, i had a few thoughts while doing this, which i don't know the answers to (yet...)
  • how many finished 9x9 sudoku grids are there?
  • how do you create the starting grids - is it simply backtracking from a finished square that fulfills the constraints?
  • in connection with the previous, it should be noted that most starting grids i've seen have 180 degree rotational symmetry about a diagonal, sometimes 90 degree about both or reflectional about both, just like crossword grids
  • is there a way to determine the 'difficulty' of a particular starting grid deterministically, or is it purely subjective?

if anyone has any ideas, i'd be interested...

1 comment:

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cool blog. I always tru to win the game but till i haven't. Hope for the best. Anyways i love playing this game.