in reply to Rolling DND Dice.

Suggestions for how to make this smaller and Perlisher are welcome. I'm sure this can be compressed to a one-liner, somehow...

Heres my go at a generic version. Returns the average of NdS Drop X. N,S should be larger than 0 and X non-negative. eg: avg_die(4,6,1) gives your result (in 162 chars, including sub decl. :-) 

#!perl -l
use strict;
use warnings;
$|++;
#162 chars, including sub decl.
sub A{my($d,$s,$l,$y,$c,$t,$z)=@_;$c||=\$z;if(!$d){
$t+=$_ for(sort{$a<=>$b}@$y)[$l..$#$y];$$c++}else{$t+=A
($d-1,$s,$l,[@{$y||[]},$_],$c)for 1..$s}$y?$t:$t/$z}

[download]

sub avg_roll{
    my($num_dice,
       $sides_of_dice,
       $num_to_lose,
       # We only expect the below to be provided when called
       # recursively
       $rolled_ref,
       $counter_ref)=@_;

    my ($total,$counter); # we declare these with the @_ in the golf
                          # version here we seperate them to show they
                          # arent really parameters.
    $counter_ref||=\$counter; # make a reference to our counter,
                             # unless we were called recursively;
    unless ($num_dice){ # we are done, no more dice

        $total+=$_ # increment the total by the value of the dice
          for (
            sort {$a<=>$b} @$rolled_ref    # sort the results numerica
+lly
                                           # to make avg_roll(4,12,1) 
+work.
          )[$num_to_lose..$#$rolled_ref];  # take a slice
        $$counter_ref++                    # incrememnt the counter
    } else { # we havent finished rolling
        $total+=                     # so increment the total
            avg_roll(                # by the result
               $num_dice-1,          # of the next die
                $sides_of_dice,
                $num_to_lose,
               [                     # pass in a ref,
                 @{$rolled_ref||[]}, # containing the previous rolls
                 $_                  # and the new one
               ],
               $counter_ref          # and a way to access the counter
            )
            for 1..$sides_of_dice    # for each possible roll of the d
+ie
    }
    $rolled_ref ? $total             # if we are not the root of the r
+ecursion
                                     # return the total, whatever it m
+ay be
                : $total/$counter    # return the average.
}

[download]
print A(4,6,1);
print avg_roll(4,6,1);
__END__
12.2445987654321
12.2445987654321

[download]

Update: 150 chars.

sub B{my($d,$s,$l,$c,@y,$t,$z)=@_;$c||=\$z;if(!$d){$t+=$_
for(sort{$a<=>$b}@y)[$l..$#y];$$c++}else{$t+=B($d-1,$s,$l,
$c,@y,$_)for 1..$s}@y?$t:$t/$z}

[download]

:-)


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