#!perl

use strict;

my %data = (
			'sort 1' => {'a.b.c' => ['19:20', '20:30'],
						 'a.b.d' => ['15:10', '19:40']},
			'sort 2' => {'e.f.g' => ['12:13'],
						 'g.h.i' => ['8:15', '23:11']});

my %times;

foreach my $sorter (values %data) {
	foreach my $domain (keys %$sorter) {
		foreach my $time (@{$sorter->{$domain}}) {
			push(@{$times{$time}}, $domain);
		}
	}
}

foreach my $time (sort { cmpTime($a, $b) } keys %times) {
	foreach my $domain (@{$times{$time}}) {
		print "domain: $domain, time: $time\n";
	}
}

sub cmpTime {
	my ($t1, $t2) = @_;
	my ($h1, $m1) = split(/:/, $t1);
	my ($h2, $m2) = split(/:/, $t2);
	return 60*$h1 + $m1 <=> 60*$h2 + $m2;
}