#!/usr/bin/perl

use warnings;
use strict;

#example data below.
my %data = (
        #Partno    List of orders
        "A1111" => [qw/12345 1234 123456 2345 233 23456/],
        "B2222" => [qw/12345/],
        "C3333" => [qw/12345 6789/],
        "D4444" => [qw/12345 1234 6789/],
        "E5555" => [qw/12345 1234 6789 99999 999999 444444 22222 111/],
        "F6666" => [qw/888888 9999999 6789/],
);


#Find the 5 numerically largest orders for each partno, and display them.

foreach my $part_no (sort keys %data) {
        my @matching_orders;

        #Sort each order by number, largest first..
        @matching_orders = sort { $a <=> $b } @{$data{$part_no}};

        #We want upto the most recent five. Nasty hack.
        my $idx = $#matching_orders-4;
        $idx = 0 if($idx < 0);
        my @top_five = reverse splice @matching_orders, $idx;
        $data{$part_no} = \@top_five;
}

#I now know the first element of each part_no array is
#the largest order number that part_no appears on.
#sort by that element.

foreach my $part_no (sort { ${$data{$a}}[0] <=> ${$data{$b}}[0] } keys %data) {
        #Now display them
        print "Part Number \"$part_no\" was found on: ";
        print join ", ", @{$data{$part_no}};
        print "\n";
}