#!/usr/bin/env php
<?php declare(strict_types=1);

$inputStr = file_get_contents('input.txt');
$input = str_split($inputStr);
$actions = array_map(fn (string $item): int => $item === '(' ? 1 : -1, $input);

echo "Part 1: final floor:";
echo array_reduce($actions, fn (int $a, int $b): int => $a + $b, 0) . "\n";

function find_sum_index(array $actions, int $target = -1): int
{
    $current = 0;

    foreach ($actions as $idx => $val)
    {
        $current += $val;

        if ($current === $target)
        {
            return $idx + 1;
        }

    }
}

echo "Part 2: first step in basement:";
echo  find_sum_index($actions, -1) . "\n";