check out the following:

use strict;
use Data::Dumper;

my %hash=();
while(my $line=<DATA>){
    chomp $line;
    my($key,$val)=split(/\s+=>\s+/,$line);
    my ($j,@k)=split(/[\|]/,$val);
    my $realkey=join('|',@k);
    if ( ! exists($hash{$realkey}) ){
        $hash{$realkey}=[];
    }
    push @{$hash{$realkey}},$key;
}

print Dumper(\%hash);


__END__
5030 => 5030|RED DOOR|10-14
1049 => 1049|RED DOOR|10-14
4990 => 4990|RED DOOR|10-14
959  => 959|RED DOOR|10-14
15047 => 15047|FLOWER|13+
5565 => 5565|RED DOOR|10-14
4449 => 4449|RED DOOR|10-14
1065 => 1065|RED DOOR|10-14
2992 => 2992|RED DOOR|10-14
4956 => 4956|RED DOOR|10-14
17665 => 17665|FLOWER|13+
6217 => 6217|RED DOOR|10-14
1224 => 1224|RED DOOR|10-14
424 => 424|RED DOOR|10-14
368 => 368|RED DOOR|10-14
451 => 451|RED DOOR|10-14
7752 => 7752|RED DOOR|10-14
4070 => 4070|RED DOOR|10-14
1312 => 1312|RED DOOR|10-14
17668 => 17668|FLOWER|13+
4224 => 4224|RED DOOR|10-14
3588 => 3588|RED DOOR|10-14
11076 => 11076|RED DOOR|10-14
2986 => 2986|RED DOOR|10-14
2402 => 2402|RED DOOR|10-14
10834 => 10834|RED DOOR|10-14
849 => 849|RED DOOR|10-14
2954 => 2954|RED DOOR|10-14
11 => 11|RED DOOR|10-14
4093 => 4093|RED DOOR|10-14
492 => 492|RED DOOR|10-14
1861 => 1861|RED DOOR|10-14
4384 => 4384|RED DOOR|10-14
15037 => 15037|FLOWER|11+
13044 => 13044|FLOWER|13+
899 => 899|RED DOOR|10-14
292 => 292|RED DOOR|10-14
10421 => 10421|RED DOOR|10-14
4120 => 4120|RED DOOR|10-14
5557 => 5557|RED DOOR|10-14
3859 => 3859|RED DOOR|10-14
930 => 930|RED DOOR|10-14
649 => 649|RED DOOR|10-14
7511 => 7511|RED DOOR|10-14
648 => 648|RED DOOR|10-14
73 => 73|RED DOOR|10-14
12537 => 12537|RED DOOR|10-14
2485 => 2485|RED DOOR|10-14
[download]

which when run gives you:

$VAR1 = {
          'FLOWER|11+' => [
                            '15037'
                          ],
          'RED DOOR|10-14' => [
                                '5030',
                                '1049',
                                '4990',
                                '959',
                                '5565',
                                '4449',
                                '1065',
                                '2992',
                                '4956',
                                '6217',
                                '1224',
                                '424',
                                '368',
                                '451',
                                '7752',
                                '4070',
                                '1312',
                                '4224',
                                '3588',
                                '11076',
                                '2986',
                                '2402',
                                '10834',
                                '849',
                                '2954',
                                '11',
                                '4093',
                                '492',
                                '1861',
                                '4384',
                                '899',
                                '292',
                                '10421',
                                '4120',
                                '5557',
                                '3859',
                                '930',
                                '649',
                                '7511',
                                '648',
                                '73',
                                '12537',
                                '2485'
                              ],
          'FLOWER|13+' => [
                            '15047',
                            '17665',
                            '17668',
                            '13044'
                          ]
        };
[download]

Now... your challenge is to understand what the code is doing. :-)