Advent of code 2020/8

Ajax Direct

$cmds = (array) $input->lines->map(function ($line) {
    [$action, $num] = $line->split(" ");
    return [(string) $action, int($num)];
});

function run($cmds) {
    $runs = [];
    $acc  = 0;
    for ($i = 0; $i < count($cmds); $i++) {
        if (in_array($i, $runs)) return [false, $acc];
        $runs[] = $i;
        match ($cmds[$i][0]) {
            "jmp" => $i += ($cmds[$i][1] - 1),
            "acc" => $acc += $cmds[$i][1],
            default => null,
        };
    }
    return [true, $acc];
}

// ==================================================
// > PART 1
// ==================================================
[$_, $solution_1] = run($cmds);

// ==================================================
// > PART 2
// ==================================================
foreach ($cmds as $i=>$cmd) {
    $replace = ["jmp" => "nop", "nop" => "jmp"][$cmd[0]] ?? false;
    if (!$replace) continue;

    $try = $cmds;
    $try[$i][0] = $replace;

    [$finish, $solution_2] = run($try);
    if ($finish) break;
}