77 lines
2.1 KiB
Kotlin
77 lines
2.1 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.Groups
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private data class PlayedGame(val a: List<Int>, val b: List<Int>)
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@Day(22)
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class Day22(@Groups val input: List<List<String>>) {
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private val one = input[0].drop(1).map { it.toInt() }
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private val two = input[1].drop(1).map { it.toInt() }
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fun part1(): Long {
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val oneDeque = ArrayDeque(one)
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val twoDeque = ArrayDeque(two)
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while (oneDeque.isNotEmpty() && twoDeque.isNotEmpty()) {
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val a = oneDeque.removeFirst()
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val b = twoDeque.removeFirst()
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if (a > b) {
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oneDeque.addLast(a)
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oneDeque.addLast(b)
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} else {
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twoDeque.addLast(b)
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twoDeque.addLast(a)
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}
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}
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val deque = if (oneDeque.isEmpty()) twoDeque else oneDeque
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return deque.score()
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}
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private fun ArrayDeque<Int>.score() =
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asReversed().mapIndexed { index, value -> (index + 1).toLong() * value.toLong() }.sum()
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fun part2(): Long {
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val oneDeque = ArrayDeque(one)
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val twoDeque = ArrayDeque(two)
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val winner = playGame(oneDeque, twoDeque)
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val deque = if (winner == 1) oneDeque else twoDeque
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return deque.score()
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}
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private fun playGame(one: ArrayDeque<Int>, two: ArrayDeque<Int>): Int {
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val playedGames = mutableSetOf<PlayedGame>()
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while (one.isNotEmpty() && two.isNotEmpty()) {
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if (!playedGames.add(PlayedGame(one.toList(), two.toList()))) return 1
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val a = one.removeFirst()
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val b = two.removeFirst()
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val winner = when {
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one.size >= a && two.size >= b -> playGame(
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ArrayDeque(one.take(a)),
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ArrayDeque(two.take(b))
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)
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a > b -> 1
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else -> 2
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}
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if (winner == 1) {
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one.addLast(a)
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one.addLast(b)
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} else {
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two.addLast(b)
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two.addLast(a)
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}
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}
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return if (one.isEmpty()) 2 else 1
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}
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}
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