#!/usr/bin/perl -w

use constant HIGH => 10_000;
my $ans = 0;

$ans = int(rand(HIGH)) + 1;

&cleverGuess(1, HIGH);

sub cleverGuess {

   my( $lower, $higher ) = @_;                                                                             
   my $guess = int(($lower + $higher)/2);
   print "Guessing: $guess\n";

   if ($guess == $ans) {
      print "The guess was correct!";
   }

   elsif ($ans < $guess) {
      print "Lower...";
      cleverGuess($lower, $guess-1);
   }

   else {
      print "Higher...";
      cleverGuess( $guess + 1, $higher );
   }
}