Advent of code 2023/1

Ajax Direct

function solve($lines) {
    return $lines->map(function ($l) {
        $nums = $l->chars()->keep(range(0, 9));
        return (int) ($nums->first() . $nums->last());
    })->sum();
}

// ==================================================
// > PART 1
// ==================================================
$solution_1 = solve($input->lines);

// ==================================================
// > PART 2
// ==================================================
$digits = [
    "zero"  => 0,
    "one"   => 1,
    "two"   => 2,
    "three" => 3,
    "four"  => 4,
    "five"  => 5,
    "six"   => 6,
    "seven" => 7,
    "eight" => 8,
    "nine"  => 9,
];

$solution_2 = solve($input->lines->map(fn ($l) =>
    scalar(preg_replace_callback("/(".implode("|", array_keys($digits)).")/", fn ($r) =>
        $digits[$r[1]]
    , (string) $l))
));