# The Fisher-Yates Shuffle 
sub Shuffle
{
    my $arrayref = shift;
    my $index = @$arrayref;
    while ( $index-- ) 
    {
        my $newloc = int rand (1+$index);
        # next if $index == $newloc; # Not needed in Perl.
        @$arrayref[$index, $newloc] = @$arrayref[$newloc, $index];
    }
}