[EMAIL PROTECTED] wrote: > Thought I'd offer a method for solving all possible 9x9 sudoku puzzles > in one go. It'll takes a bit of time to run however (and 9x9 seems to > be about as big as is reasonably possible before combinatorial > explosion completely scuppers this type of program)... > > Basic idea:- > > Start with a grid initialised with: > > 123456789 > 234567891 > 345678912 > 456789123 > 567891234 > 678912345 > 789123456 > 891234567 > 912345678 > > Note that all rows and columns contain all 9 digits (but that the > sub-tiles aren't correct for a sudoku solution). > > Next write a program which permutes all 9 columns, and then for each of > those permutations permutes the last 8 rows. This will, I believe, > generate all possible grids with no digit repetitions in any row or > column. It will generate 14,631,321,600 (9!*8!) possible sudoku > candidates. Finally, check each candidate to see if any 3x3 subtile has > a repeated digit in it and discard as soon as a repeat is found (sooner > the better). Any that come through unscathed get written as a 82 (81 + > lf) char string to an output file.
I'm having trouble coming up with anything that fits this grid: ..12..... ..2x..... ......... ......... ......... ......... ......... ......... ......... where x is not 3, by permuting columns, then rows. You may also have to permute the numbers. Although, even then, x=1 is still impossible. -- http://mail.python.org/mailman/listinfo/python-list