63 lines
1.5 KiB
Scala
63 lines
1.5 KiB
Scala
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package aoc.day15
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import aoc._
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import scala.collection.mutable
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val instructionStrings = lines.next().split(',').toSeq
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// part 1
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extension (s: String)
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def day15Hash =
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s.foldLeft(0)((a, b) => ((a + b) * 17) & 255)
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def part1 =
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println(instructionStrings.map(_.day15Hash).sum)
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// part 2
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enum Ins:
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case Del(label: String)
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case Add(label: String, length: Int)
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def hash = this match
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case Del(label) => label.day15Hash
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case Add(label, length) => label.day15Hash
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import Ins._
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object Parser extends CommonParser:
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val insKind =
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"""[a-z]+""".r.flatMap { label =>
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("-" ^^^ Del(label)) |
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("=" ~ num ^^ { case _ ~ num => Add(label, num) })
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}
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def apply(s: String) = parse(insKind, s).get
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val instructions = instructionStrings.map(Parser(_))
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class Sim(ss: Seq[Ins]):
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private val boxes = (0 to 255).map(_ => mutable.ArrayBuffer.empty[Add]).toArray
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def handle(ins: Ins): Unit = ins match
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case a @ Add(label, length) =>
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boxes(ins.hash).indexWhere(_.label == label) match
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case -1 => boxes(ins.hash).append(a)
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case pos => boxes(ins.hash)(pos) = a
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case Del(label) => boxes(ins.hash).filterInPlace(_.label != label)
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ss.foreach(handle)
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def remain =
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boxes.toIterator.zipWithIndex.flatMap { (box, idx) =>
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box.toIterator.zipWithIndex.map { (add, pos) =>
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(idx + 1, pos + 1, add.length)
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}
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}
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def part2 =
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println(Sim(instructions).remain.map(_ * _ * _).sum)
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@main def Day15(part: Int) = part match
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case 1 => part1
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case 2 => part2
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