51 lines
1.3 KiB
Kotlin
51 lines
1.3 KiB
Kotlin
package be.vandewalleh.aoc.days
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import be.vandewalleh.aoc.utils.input.Day
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import be.vandewalleh.aoc.utils.input.Input
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import be.vandewalleh.aoc.utils.input.Lines
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import be.vandewalleh.aoc.utils.input.createDay
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import org.eclipse.collections.api.list.primitive.MutableIntList
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import org.eclipse.collections.impl.factory.primitive.IntLists
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import org.eclipse.collections.impl.factory.primitive.IntLongMaps
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@Day(10)
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class Day10(@Lines val input: Input<IntArray>) {
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fun part1(): Int {
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val sorted = IntLists.mutable.of(0, *input.value).apply {
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sortThis()
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add(last + 3)
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}.toArray().toList()
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var ones = 0
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var threes = 0
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sorted.zipWithNext().forEach { (a, b) ->
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if (a + 1 == b) ones++
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else if (a + 3 == b) threes++
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}
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return ones * threes
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}
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fun part2(): Long {
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val sorted: MutableIntList = IntLists.mutable.of(*input.value).apply { sortThis() }
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val map = IntLongMaps.mutable.empty().apply {
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put(0, 1L)
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}
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sorted.forEach { i ->
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map.put(i, map.get(i - 1) + map.get(i - 2) + map.get(i - 3))
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}
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return map.get(sorted.last)
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}
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}
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fun main() = with(createDay<Day10>()) {
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println(part1())
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println(part2())
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}
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