#!/usr/bin/perl

# SPDX-FileCopyrightText: Chris Pressey, the original author of this work, has dedicated it to the public domain.
# For more information, please refer to <https://unlicense.org/>
# SPDX-License-Identifier: Unlicense

my %rule = (
	'11' => '12',
	'12' => '122',
	'21' => '112',
	'22' => '1122'
);

my $k = "122112122122112112212112122";

my $s = '122';
my $p = '';
my $n = 1;
my $t = 16;

sub square($rule) {
	my $newrule = +{};
	foreach my $i (sort keys %$rule) {
		foreach my $j (sort keys %$rule) {
			$newrule->{$i . $j} = $rule->{$i} . $rule->{$j};
		}
	}
	return $newrule;
	# remember to double len
}

my $len = 2;

foreach my $k (sort keys %rule) {
	print "$k -> $rule{$k}\n";
}
print "\n";

print "K: $k...\n";
print "0: $s\n";
my $spc = (' ' x $len);

while ($n <= $t) {
	my $h = substr($s, 0, $len);
	my $r = substr($s, $len);
	my $z = $rule{$h};
	#print "$n: $p  $k  $r+$z\n";
	$s = $r . $z;
	print "$n: ${spc}$s\n";
	# $p .= $k;
	$spc .= (' ' x $len);
	$n++;
}