AoC | Day 1 | Part 2

package year_2023.day_1
fun partTwo() {
    println("[2023] Day one, part two...")

    val validNumbers = mapOf(
        "one" to 1,
        "two" to 2,
        "three" to 3,
        "four" to 4,
        "five" to 5,
        "six" to 6,
        "seven" to 7,
        "eight" to 8,
        "nine" to 9
    )

    val numbers = input().split("\n")
        .map { line ->
            val firstDigit = line.firstOrNull { it.isDigit() }?.let { it.toString() to line.indexOf(it) }
            val firstWord = validNumbers.keys.mapNotNull { key ->
                if (line.contains(key)) {
                    return@mapNotNull validNumbers[key]!!.toString() to line.indexOf(key)
                }

                null
            }.minByOrNull { it.second }

            val lastDigit = line.lastOrNull { it.isDigit() }?.let { it.toString() to line.lastIndexOf(it) }
            val lastWord = validNumbers.keys.mapNotNull { key ->
                if (line.contains(key)) {
                    return@mapNotNull validNumbers[key]!!.toString() to line.lastIndexOf(key)
                }

                null
            }.maxByOrNull { it.second }

            val first = listOf(firstDigit, firstWord).minBy { it?.second ?: Int.MAX_VALUE }!!.first
            val last = listOf(lastDigit, lastWord).maxBy { it?.second ?: Int.MIN_VALUE }!!.first

            "$first$last".toInt()
        }

    val sum = numbers.sum()
    println(sum)
}