use strict;
use warnings;

use constant HIGH => 1024;

my $the_number = int(rand HIGH) + 1;
print "The number is $the_number\n";
my $high;
my $low;
my $answer;
my $guess;
ask_question();

sub ask_question {
	sleep(1);
	if (!$answer) {
		$high = HIGH;
		$low = 1;
	} elsif ($answer == 0) {
		return;
	} elsif ($answer == 1) {
		$low = $guess + 1;
	} elsif ($answer == -1) {
		$high = $guess - 1;
	}
	$guess = int(($low + $high) / 2);
	print "Is your number $guess? ";
	answer();
}

sub answer {
	if ($guess < $the_number) {
		print "Go higher ...\n";
		$answer = 1;
		ask_question();
	} elsif ($guess == $the_number) {
		print "You got it!\n";
		$answer = 0;
	} else {
		print "Go lower ...\n";
		$answer = -1;
		ask_question();
	}	 
}