#!/usr/bin/env perl
use strict;
use warnings;

use Data::Dumper;

my %info_for;
for my $file (@ARGV) {
    open my $FH, '<', $file or die $!;
    while ( my $line = <$FH> ) {
        my ( $cake, $price ) = split /;/, $line, 3;
        push @{ $info_for{$cake}{files} }, $file;
        push @{ $info_for{$cake}{prices} }, $price;
    }
    close $FH;
}
print Dumper \%info_for;

exit 0;

__END__
$VAR1 = {
          'cake_2' => {
                        'files' => [
                                     'cakes1.txt',
                                     'cakes2.txt',
                                     'cakes3.txt'
                                   ],
                        'prices' => [
                                      '4',
                                      '5',
                                      '4'
                                    ]
                      },
          'cake_10' => {
                         'files' => [
                                      'cakes2.txt'
                                    ],
                         'prices' => [
                                       '1'
                                     ]
                       },
          'cake_9' => {
                        'files' => [
                                     'cakes1.txt'
                                   ],
                        'prices' => [
                                      '8'
                                    ]
                      },
          'cake_4' => {
                        'files' => [
                                     'cakes1.txt'
                                   ],
                        'prices' => [
                                      '7'
                                    ]
                      },
          'cake_6' => {
                        'files' => [
                                     'cakes2.txt'
                                   ],
                        'prices' => [
                                      '9'
                                    ]
                      },
          'cake_1' => {
                        'files' => [
                                     'cakes1.txt',
                                     'cakes2.txt',
                                     'cakes3.txt'
                                   ],
                        'prices' => [
                                      '3',
                                      '5',
                                      '3'
                                    ]
                      },
          'cake_3' => {
                        'files' => [
                                     'cakes1.txt',
                                     'cakes2.txt',
                                     'cakes3.txt'
                                   ],
                        'prices' => [
                                      '9',
                                      '5',
                                      '9'
                                    ]
                      }
        };