my @typeset = qw(P K L G);
my $length = 10;
strangemultiset($length, \@typeset, 0, '');

sub strangemultiset
{
    my ($len, $set, $start, $string) = @_;
    if ($len == 0) {
        print "$string\n";
        return;
    }
    
    my $max = $len - @$set + $start + 1;
    my $min = $start == @$set - 1 ? $max : 1;
    for my $currentLen ($min..$max) {
        strangemultiset($len-$currentLen, $set, $start + 1, $string . ($set->[$start] x $currentLen));
    }
}