Advent of Code day 5 - part 1

day5.php

<?php
$input = file('input.txt', FILE_IGNORE_NEW_LINES);
//$input = file('sample.txt', FILE_IGNORE_NEW_LINES);

$seeds = explode(' ', str_replace('seeds: ', '', $input[0]));
$seedToSoilMap = getMapByHeader($input, 'seed-to-soil map:');
$soilToFertilizerMap = getMapByHeader($input, 'soil-to-fertilizer map:');
$fertilizerToToWaterMap = getMapByHeader($input, 'fertilizer-to-water map:');
$waterToLightMap = getMapByHeader($input, 'water-to-light map:');
$lightToTemperatureMap = getMapByHeader($input, 'light-to-temperature map:');
$temperatureToHumidityMap = getMapByHeader($input, 'temperature-to-humidity map:');
$humidityToLocationMap = getMapByHeader($input, 'humidity-to-location map:');

$locations = [];
foreach ($seeds as $seed) {
    $soilForSeed = getDestinationForSource($seed, $seedToSoilMap);
    //printf('seed %s moet in soil %s' . PHP_EOL, $seed, $soilForSeed);
    $fertilizerForSoil = getDestinationForSource($soilForSeed, $soilToFertilizerMap);
    //printf('soil %s moet in fertilizer %s' . PHP_EOL, $soilForSeed, $fertilizerForSoil);
    $waterForFertilizer = getDestinationForSource($fertilizerForSoil, $fertilizerToToWaterMap);
    //printf('fertilizer %s moet in water %s' . PHP_EOL, $fertilizerForSoil, $waterForFertilizer);
    $lightForWater = getDestinationForSource($waterForFertilizer, $waterToLightMap);
    $tempForLight = getDestinationForSource($lightForWater, $lightToTemperatureMap);
    $humidityToTemp = getDestinationForSource($tempForLight, $temperatureToHumidityMap);
    $locationForHumidity = getDestinationForSource($humidityToTemp, $humidityToLocationMap);
    $locations[] = $locationForHumidity;
    printf('seed %s moet in location %s' . PHP_EOL, $seed, $locationForHumidity);
}
printf('en de laagste location is dus %s' . PHP_EOL, min($locations));

function getDestinationForSource(int $seed, array $map)
{
    $sources = $map['source'];
    $destinations = $map['destination'];
    foreach ($sources as $i => $source) {
        if ($source['start'] <= $seed && $source['end'] >= $seed) {
            return $seed + ($destinations[$i]['start'] - $source['start']);
        }
    }

    return $seed;
}

function getMapByHeader(array $input, string $header): array
{
    $mapLines = [];
    $found = false;
    foreach ($input as $i => $line) {
        if ($line == '' && $found) {
            break;
        }
        if ($found) {
            $mapLines[] = $line;
        }
        if ($line == $header) {
            $found = true;
        }
    }

    $map = ['destination' => [], 'source' => []];
    foreach ($mapLines as $mapLine) {
        $nums = explode(' ', $mapLine);
        $map['destination'][] = [
            'start' => intval($nums[0]),
            'length' => intval($nums[2]),
            'end' => $nums[0] + $nums[2] - 1,
        ];
        $map['source'][] = [
            'start' => intval($nums[1]),
            'length' => intval($nums[2]),
            'end' => $nums[1] + $nums[2] - 1,
        ];
    }

    return $map;
}

function dd($a, $b = null, $c = null, $d = null)
{
    die(var_dump($a, $b, $c, $d));
}