59 lines
1.3 KiB
Scala
59 lines
1.3 KiB
Scala
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package aoc
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package day04
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import scala.collection.mutable
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val dayNumber = "04"
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@main def part1: Unit =
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println(part1(loadInput(dayNumber)))
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@main def part2: Unit =
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println(part2(loadInput(dayNumber)))
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def part1(input: String): String =
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input
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.split('\n')
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.map { case s"$_: $winning | $numbers" =>
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(
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winning.split(" ").flatMap(_.toIntOption),
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numbers.split(" ").flatMap(_.toIntOption)
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)
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}
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.map((w, n) => w.intersect(n).length)
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.filter(_ > 0)
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.map(l => Math.pow(2, l - 1).toInt)
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.sum
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.toString
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def part2(input: String): String =
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final case class Card(
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matchingCards: List[Int],
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instances: Int = 1
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):
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def addInstances(n: Int) = copy(instances = instances + n)
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val cards =
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input
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.split('\n')
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.map { case s"$_: $winning | $numbers" =>
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winning
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.split(" ")
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.flatMap(_.toIntOption)
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.intersect(numbers.split(" ").flatMap(_.toIntOption))
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.length
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}
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.zipWithIndex
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.map((count, index) => Card((1 to count).map(_ + index).toList))
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.to(mutable.ArraySeq)
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for card <- cards do
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for index <- card.matchingCards do
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cards.update(index, cards(index).addInstances(card.instances))
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cards
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.map(_.instances)
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.sum
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.toString
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