AoC | Day 5 | Part 2

package year_2023.day_5

import kotlin.math.absoluteValue

fun partTwo() {
    println("[2023] Day five, part two...")

    val inputData = input()

    fun getMap(mapName: String): List<Pair<LongRange, LongRange>> {
        val map = inputData.split("\n\n")
            .single { it.contains(mapName) }
            .substringAfter("$mapName map:")
            .trim()
            .split("\n")
            .map { it.split(" ") }
            .map {
                val startSource = it[1].toLong()
                val startTarget = it[0].toLong()
                val range = it[2].toLong()
                (startSource until startSource + range) to (startTarget until startTarget + range)
            }

        return map
    }

    val seeds = inputData.split("\n\n")[0]
        .substringAfter(":")
        .trim()
        .split(" ")
        .map { it.toLong() }
        .windowed(2, 2)
        .map {
            it[0] until it[0] + it[1]
        }

    val seedToSoilRanges = getMap("seed-to-soil")
    val soilToFertilizerRanges = getMap("soil-to-fertilizer")
    val fertilizerToWaterRanges = getMap("fertilizer-to-water")
    val waterToLightRanges = getMap("water-to-light")
    val lightToTemperatureRanges = getMap("light-to-temperature")
    val temperatureToHumidityRanges = getMap("temperature-to-humidity")
    val humidityToLocationRanges = getMap("humidity-to-location")

    fun getPrevious(map: List<Pair<LongRange, LongRange>>, source: Long): Long {
        val ranges = map.firstOrNull { it.second.contains(source) }
            ?: return source

        return ranges.first.first + (source - ranges.second.first).absoluteValue
    }

    var minValue = Long.MAX_VALUE

    for (location in 1 until 100_000_000L) {
        val humidity = getPrevious(humidityToLocationRanges, location)
        val temperature = getPrevious(temperatureToHumidityRanges, humidity)
        val light = getPrevious(lightToTemperatureRanges, temperature)
        val water = getPrevious(waterToLightRanges, light)
        val fertilizer = getPrevious(fertilizerToWaterRanges, water)
        val soil = getPrevious(soilToFertilizerRanges, fertilizer)
        val seed = getPrevious(seedToSoilRanges, soil)

        if (seeds.any { it.contains(seed) }) {
            minValue = location
            break
        }
    }

    println(minValue)
}