#! perl -slw
use strict;
use Data::Dumper;

my $regex = qr/(\d\d):(\d\d)(?::(\d\d))?/;

#             01234567890123456
my $string = "11:30 or 11:29:53";

my $res;

$res->{$-[0]} = [grep $_, $1, $2, $3] while $string =~ /$regex/g;

print Dumper $res;

__END__
c:\test>225814
$VAR1 = {
          '0' => [
                   '11',
                   '30'
                 ],
          '9' => [
                   '11',
                   '29',
                   '53'
                 ]
        };


c:\test>