private fun parse(input: String): Map<String, List<String>> = input.lines().mapNotNull { line ->
    val split = line.indexOf(':')
    if (split == -1) null else line.take(split) to line.drop(split + 1).split(' ')
}.toMap()

private fun Map<String, Iterable<String>>.paths(src: String, dst: String): Int {
    val cache = mutableMapOf<String, Int>()
    return DeepRecursiveFunction { key ->
        if (key == dst) 1 else cache.getOrPut(key) { get(key)?.sumOf { callRecursive(it) } ?: 0 }
    }(src)
}

fun part1(input: String): Int = parse(input).paths("you", "out")

fun part2(input: String): Long = with(parse(input)) {
    paths("svr", "dac").toLong() * paths("dac", "fft") * paths("fft", "out") +
            paths("svr", "fft").toLong() * paths("fft", "dac") * paths("dac", "out")
}