fun main() {
    fun MutableList<Char>.overallValue() = sumOf {
        if (it in 'a'..'z') {
            it - 'a' + 1
        } else {
            it - 'A' + 27
        }
    }

    fun part1(input: List<String>): Int {
        val misplacedItems = mutableListOf<Char>()
        for (line in input) {
            val left = line.substring(0, line.length/2).toHashSet()
            val right = line.substring(line.length/2).toHashSet()

            for (c in right) {
                if (left.contains(c)) {
                    misplacedItems.add(c)
                    break
                }
            }
        }
        return misplacedItems.overallValue()
    }

    fun part2(input: List<String>): Int {
        val badges = mutableListOf<Char>()
        for (group in input.chunked(3)) {
            val first = group[0].toHashSet()
            val second = group[1].toHashSet()
            val third = group[2].toHashSet()
            for (item in third) {
                if (first.contains(item) && second.contains(item)) {
                    badges.add(item)
                    break
                }
            }
        }
        return badges.overallValue()
    }

    // test if implementation meets criteria from the description, like:
    val testInput = readInput("Day03_test")
    check(part1(testInput) == 157)
    check(part2(testInput) == 70)

    val input = readInput("Day03")
    println(part1(input))
    println(part2(input))
}
