I can't golf it better, but I can fix a bug I've spotted.
If you say your animal isn't bigger than a bread box, it
guesses your animal to be "1", which isn't much fun.
These are my changes:
my %tree = (
'Is your animal larger than a breadbox' => {
'1' => 'giraffe',
'0' => 'cat',
},
); # anon hashref rather than array ref
#234567890#234567890#234567890#234567890#234567890
sub f{
($s,%t)=@_;$q=$s;do{{$v=a($q);$a=$t{$q}->{$v};$q=
$a,redo if$t{$a};$q=$s,next if a($a);$n=&t;$o=i($a
,$n);$t{$o}={0=>$t{$q}->{$v},1=>$n};$t{$q}->{$v}=
$o;$q=$s;}}while&w
}
Sorry about the extra 13 characters. ;) It's a cool
program though, I've got to admit that the idea had me stumped 'til I saw yours and Tilly's answers.
jarich
update: I can't count (or rather I forgot the indexing), 13 extra characters, not 6.