AOC-day3-p1.php

<?php

$input = str_split(file('i')[0]);

$map = [
	'^' => [1,0],
	'>' => [0,1],
	'v' => [-1,0],
	'<' => [0,-1],
];

$locations = [[0,0]];

foreach ($input as $instruction) {
    $a=end($locations);reset($locations);
    $b=$map[$instruction];
	$locations[] = [$a[0]+$b[0],$a[1]+$b[1]];
}
echo count(array_unique(array_values($locations), SORT_REGULAR));