#!/usr/bin/perl
# Raphael Robinson, as mentioned in "Metamagical Themas", Douglas Hofstadter
# This one just iterates on a string of digits.  Self-describing strings:
# 22 - 2 twos
# 21322314 - 2 ones, 3 twos, 2 threes, 1 four
# 3122331415 - 3 ones, 2 twos, 3 threes, 1 four, 1 five
# 3122331416 - 3 ones, 2 twos, 3 threes, 1 four, 1 six
# 10311233 - 1 zero, 3 ones, 1 two, 3 threes
# 1031223314 - 1 zero, 3 ones, 2 twos, 3 threes, 1 four
use strict;
use diagnostics;

my $line = "1";

$line = $ARGV[0] if defined $ARGV[0];

my $lastline = "x";
my $previouslastline = "y";
my @digitcount = (0, 0, 0, 0, 0, 0, 0, 0, 0, 0);
my @letters = ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9');
my $ord_zero = ord('0');

print $line, "\n";

while ($line ne $lastline) {
	$previouslastline = $lastline;
	$lastline = $line;

	foreach my $idx (0..9) { $digitcount[$idx] = 0; }

	my @a = split //, $line;

	foreach my $letter (@a) {
		++$digitcount[ord($letter) - $ord_zero];
	}

	$line = '';
	foreach my $idx (0..9) {
		if ($digitcount[$idx]) {
			$line .= $digitcount[$idx];
			$line .= $letters[$idx];
		}
	}

	if ($line eq $previouslastline) {
		print "Cycle\n";
		last;
	}

	print $line, "\n";
}