On Thu, 13 Nov 2008 11:10:54 -0500, Matthew Moss wrote:
> The final step is to take the "solved" puzzle and poke holes in it,
> enough so we have a real puzzle for humans to solve. Again, this is
> quite simple:
> 
>      64.times{puzzle[rand(81)] = 0}
> 
> This line will punch at most 64 holes into the puzzle. 64 is chosen as
> the upper limit, since there seems to be some evidence that the [Minimum
> Sudokus][2] -- puzzles uniquely solveable with the least number of clues
> -- seems to require 17 clues (and 81 - 17 = 64). It is quite likely,
> however, that there will be some overlap in the hole choices, and so
> there will likely be more than 17 clues: fewer holes means more clues,
> which means (generally) an easier puzzle.

This will punch out, on average, 44 holes. 




-- 
Chanoch (Ken) Bloom. PhD candidate. Linguistic Cognition Laboratory.
Department of Computer Science. Illinois Institute of Technology.
http://www.iit.edu/~kbloom1/