advent_of_code_2021/day_1/part_1.php

<?php

$numbers = array_map('intval', explode("\n", file_get_contents('input.txt')));

$current = array_shift($numbers);
$count = 0;
foreach ($numbers as $number) {
    if ($number > $current) {
        $count++;
    }

    $current = $number;
}

echo $count;