use strict;
use warnings;
use Data::Dumper;


my $MTX = [
[4,-1,-2,-2, 0,-1],
[-1,5, 0, 2,-3, 1],
[-2,0, 6, 1,-3, 5],
[-2,2, 1, 7,-3, 0],
[0,-3,-3,-3, 8,-3],
[-1,1, 5, 0,-3, 9],
];

my (@diagonal, @result);
my $k = 3;
for my $i (0..5) {
	push @diagonal, $MTX->[$i][$i];
}
for my $i (0..5) {
	for my $j (0..5) {
		for my $k (0..5) {
			next if $i == $j or $i == $k or $j == $k;
			my $sc;
			$sc += $diagonal[$_] for ($i, $j, $k);
			next unless defined $sc;
			next if $sc < 17;
			push @{$result[$sc]}, [$i, $j, $k];
		}
	}
}
print Dumper \@result;