As a follow-up... I've noticed that any duplicates in a given array will mess up the topological sort. So, I just added a quick duplicate search:
use Graph::Directed;
my @array1 = qw(dog rat rat mouse);
my @array2 = qw(dog rat mouse bird);
my @array3 = qw(cat rat fish mouse);
my @elements;
push(@elements, \@array1, \@array2, \@array3);
my $graph = Graph::Directed->new;
for (0..$#elements) {
# Check for duplicate GUIDs in this set
my %seen = ();
my @dup = ();
foreach my $item (@{$elements[$_]}) {
if ($seen{$item}++) {
push(@dup, $item);
}
}
unless ($#dup == -1) {
print "Duplicate elements: @dup";
exit;
}
# If all's well, add to the path
$graph->add_path(@{$elements[$_]});
}
my @elements_ordered = $graph->toposort;
print "@elements_ordered\n";