adventofcode/2021/6/growth.php

#!/usr/bin/env php
<?php

$input = file_get_contents("input");
$input = explode(",", $input);

$days = 80;

for($day=0; $day<$days; $day++){

	foreach($input as $i => &$v) {
		$v--;
		if($v == -1) {
			$v = 6;
			$input[] = 9;
		}
	}

}

echo "Total number of fish after $days days: " . count($input);

?>