#!/usr/local/bin/perl -w
use strict;
$|=1;

# www.PerlMonks.org 140734|(Golf) The Animal Game

# ask the question passed, return true or false
sub a($) {
	my ($qu, $ans) = (shift);
	while(!$ans) { print "\n$qu?\n"; chomp ($ans = <STDIN>) }
	$ans =~ m/y/io ? 1 : 0;
};

# ask if animal is passed value, return true or false
sub g($) {
	my ($ani, $ans) = (shift);
	while(!$ans) { print "\nis animal $ani?\n"; chomp ($ans = <STDIN>) }
	$ans =~ m/^y/io ? 1 : 0;
};

# ask what animal, return user input
sub t() {
	my $ans;
	while(!$ans) { print "\nwhat animal?\n"; chomp ($ans = <STDIN>) }
	$ans;
};

# get question to identify animal: 
# true for new, false for old; return question
sub i($$) {
	my ($old, $new, $qu) = (shift, shift);
	while(!$qu) {
		print "\nenter a question false for $old but true for $new:\n";
		chomp ($qu = <STDIN>);
	}
	$qu;
};

# ask to continue, return true or false
sub w() { a('play') ? 1 : exit 0 };

# question/answer data structure: hash of arrays
my %q = (
	"larger than a breadbox" => ['cat', 'giraffe'],
);

no strict;
while(w){($k,$v)=each%q;$k||redo;$u=$$v[a($k)];next if(g($u));while(($l,$x)=each%q){next unless$$x[0] eq $u;a($l)?$y=$$x[1]:goto N;goto E if(g($y))}N:$b=i($u,$c=t);$q{$b}=[$u,$c];E:}