14 lines
455 B
Kotlin
14 lines
455 B
Kotlin
fun main() {
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val input = generateSequence(::readLine)
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.map { it.split(")") }
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.groupBy { it[0] }
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.mapValues{ it.value.map { it[1] } }
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val rootNode = input.keys - input.values.flatten().toSet()
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println("Part 1: ${countOrbiters(input, rootNode.first(), 0)}")
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}
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fun <T>countOrbiters(graph: Map<T, List<T>>, key: T, acc: Int): Int {
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return acc + (graph[key]?.map { countOrbiters(graph, it, acc+1) }?.sum() ?: 0)
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}
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