use strict;
use warnings;

use Graph::Directed;

my $g = "Graph::Directed"->new;

$g->add_edge(split ":") for qw(
	0:6
	0:12
	0:18
	0:24
	6:12
	6:18
	6:24
	12:18
	12:24
	18:24
);

# This doesn't protect against cyclic graphs
sub paths_from_vertex
{
	my $g = shift;
	my $v = shift;
	return unless $g->has_vertex($v);
	my @s = $g->successors($v);
	return [$v] unless @s;
	my @p = map { paths_from_vertex($g, $_) } @s;
	unshift @$_, $v for @p;
	return @p;
}

sub print_path
{
	my @path = @{+shift};
	for my $i ( 0 .. $#path-1 )
	{
		print "$path[$i]:$path[$i+1] ";
	}
	print "\n";
}

for my $i (0..24)
{
	print_path($_) for paths_from_vertex($g, $i);
}