#!/usr/bin/perl -w

use strict;

my @data = (
    "3343df3ffdkj34j3k34j3k testfile1",
    "389k34d46hj3k493843kjj testfile2",
    "lj3l4o342u423see3u43u4 testfile3",

    #  Copied the first line to show that duplicates work.

    "3343df3ffdkj34j3k34j3k testfile4",   
);

{
    my %result;

    #  Loop through the array of lines.

    foreach my $line (@data) {

        #  Split the array element into hash value and filename.

        my ( $hashValue, $filename ) = split( /\s/, $line );

	#  Store the filename, indexed by hash value, into an array. This
	#  allows us to store multiple files with the same hash value.

        push( @{ $result{$hashValue} }, $filename );
    }

    #  Dump out the result hash, sorting by the hash values.

    foreach my $key ( sort keys %result ) {

	#  Dump out the array of filenames indexed by this hash value. We 
        #  could have sorted this list too if we wanted.

        foreach my $filename ( @{ $result{$key} } ) {

            print "$key -> $filename\n";
        }
    }
}