http://qs321.pair.com?node_id=267684


in reply to Re: Code to solve the "matrix formation" puzzle
in thread Code to solve the "matrix formation" puzzle

It looks like exponential-order to me. I added some code to sum up the number of permutations of the sets:
$bigtotal += Math::NumberCruncher::Permutation(scalar(@Num),MATRIX_D +IM); @Sol=CheckSolution(\@Num);
Here are the results:
Order 4: Maximum divisor is 416, solution is 2496-9152-1664-2080 Checked 19301184 cases 1445.940u 5.500s 27:10.91 88.9% 0+0k 0+0io 364pf+0w Order 3: Maximum divisor is 44, solution is 132-792-660 Checked 140526 cases 10.690u 0.050s 0:14.69 73.1% 0+0k 0+0io 364pf+0w Order 2:Maximum divisor is 7, solution is 21-84 Checked 820 cases 0.290u 0.010s 0:00.33 90.9% 0+0k 0+0io 364pf+0w
At that rate, order 5 will test about 1 billion cases and take over a day to run. But I think it might be feasible if bad solution sets are eliminated early.

The big problem is the permutations, which are factorial order. I would suggest picking the corner two items first. They have to have the same top digit. Then that determines the possible top digits of the rest of the rows.