#!/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 $k = 0 + $ARGV[0];
$|=1;
$z = 0;
while ($z < 1000000) {

	$ups = 0;
	$downs = 0;
	$k = $z;

	if ($z % 1000 == 0) {
		print "$z: ";
	}
	while ($k > 1) {
		$r = int($k / 2);
		# print "$k (= 2 x $r + 1),\n";
		if ($k % 2 == 1) {
			# print "^";
			$ups++;
			$k = $k * 3 + 1;
		} else {
			# print "v";
			$downs++;
			$k = int($k / 2);
		}
	}

	if ($z % 1000 == 0) {
		print " ($ups x ^, $downs x v)\n";
	}

	$table->{sprintf("%05d", $ups)}->{sprintf("%05d", $downs)}++;

	$z++;
}

print "\nSummary:\n";
foreach my $up_key (sort keys %$table) {
	foreach my $down_key (sort keys %{$table->{$up_key}}) {
		my $count = $table->{$up_key}->{$down_key};
		printf "%5d ^ %5d v  --> %5d x\n", $up_key, $down_key, $count;
	}
}