18 lines
1003 B
Kotlin
18 lines
1003 B
Kotlin
fun main() {
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val input = generateSequence(::readLine).map { it.split(")") }.toList()
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val parentToChildren = input.groupBy { it[0] }.mapValues { it.value.map { it[1] } }
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val rootNode = (parentToChildren.keys - parentToChildren.values.flatten().toSet()).first()
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println("Part 1: ${countOrbiters(parentToChildren, rootNode, 0)}")
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val childToParent = input.associateBy { it[1] }.mapValues { it.value[0] }
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val santaParents = getParents(childToParent, "SAN")
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val myParents = getParents(childToParent, "YOU")
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val commonParent = myParents.toSet().let { s -> santaParents.first { it in s } }
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println("Part 2: ${santaParents.indexOf(commonParent) + myParents.indexOf(commonParent)}")
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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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acc + (graph[key]?.map { countOrbiters(graph, it, acc+1) }?.sum() ?: 0)
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fun <T> getParents(graph: Map<T, T>, key: T): List<T> =
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graph[key]?.let { curr -> listOf(curr) + getParents(graph, curr) } ?: emptyList()
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