#!/usr/bin/perl
use strict;
use warnings;

use Clone qw( clone );
$|++;

my $width  = 29;
my $height = 29;

my $world = [
#0        1         2         3
#123456789012345678901234567890
'                              ',#1
' 00                           ',#2
' 0                            ',#3
'     0                        ',#4
'    00                        ',#5
'                              ',#6
'                              ',#7
'                              ',#8
'                              ',#9
'                              ',#10
'                              ',#1
'            000               ',#2
'                              ',#3
'                              ',#4
'                              ',#5
'                              ',#6
'                              ',#7
'                              ',#8
'                              ',#9
'                              ',#20
'                              ',#1
'                              ',#2
'                              ',#3
'                              ',#4
'                              ',#5
'                              ',#6
'                              ',#7
'                              ',#8
'                              ',#9
'                              ',#30
]
;


my $i = 0;
print_world($world);
while (<>) {
	chomp; exit if $_ eq 'q';
	print "iteration:", $i++, "\n";
	$world = iterate($world);
	print_world($world);

}

sub print_world {
	my $world = shift;
	for my $row (@$world) {
      print "$row\n";
   }
};


sub iterate {
   my $world = shift;
   my $new_world = clone($world);
   for my $x (0 .. $width) {
      for my $y (0 .. $height) {
         my $n = 0;
         for my $xc (-1,0,1) {
            for my $yc ( -1,0,1) {
               next if $xc == 0 and $yc == 0;

               my $tx  = $x+$xc;
               next if $tx > $width or $tx < 0;

               my $ty = $y + $yc;
               next if $ty > $height or $ty < 0;

               #warn "$x + $xc = $tx\t$y + $yc = $ty";

               my $tmp = substr($world->[$ty], $tx,1);
               $n++ if $tmp eq '0';
            }
         }

         substr($new_world->[$y], $x,1) = ' ' if $n  < 2 or $n > 3;
         substr($new_world->[$y], $x,1) = '0' if $n == 3;
      }
   }
   return $new_world;
};