101 lines
2.9 KiB
Scala
101 lines
2.9 KiB
Scala
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import scala.io.Source
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import scala.util.chaining.*
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object Day14 extends App:
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val input = Source
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.fromURL(getClass.getResource("day14Input.txt"))
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.mkString
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.split('\n')
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.toList
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enum Block:
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case Sand, Rock, Air
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object Block:
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val show: Block => String =
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case Sand => "o"
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case Rock => "#"
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case Air => "."
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type Point = (Int, Int)
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extension (point: Point)
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def x = point._1
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def y = point._2
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final case class Grid(blocks: Map[Point, Block]):
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val blocksWithDefault = blocks.withDefaultValue(Block.Air)
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val lowestLevel = blocks.keySet.map(_.y).max
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def show =
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(for
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x <- blocks.keySet.map(_.x).min to blocks.keySet.map(_.x).max
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y <- blocks.keySet.map(_.y).min to blocks.keySet.map(_.y).max
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yield ((x, y), blocksWithDefault((x, y))))
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.groupBy(_._1.y)
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.toList
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.sortBy(_._1)
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.map(_._2.sortBy(_._1.x).map(p => Block.show(p._2)).mkString)
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.mkString("\n")
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def applyGravityToSand(sand: Point): Point =
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if blocksWithDefault(sand.x, sand.y + 1) == Block.Air then (sand.x, sand.y + 1)
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else if blocksWithDefault(sand.x - 1, sand.y + 1) == Block.Air then (sand.x - 1, sand.y + 1)
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else if blocksWithDefault(sand.x + 1, sand.y + 1) == Block.Air then (sand.x + 1, sand.y + 1)
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else sand
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def dropSand(sand: Point): Option[Grid] =
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val finalPosition = LazyList
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.iterate(sand)(applyGravityToSand)
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.sliding(2)
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.takeWhile {
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case LazyList(p1, p2) => p1 != p2 && p2.y <= lowestLevel
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case _ => false
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}
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.toList
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.lastOption
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.flatMap(_.lastOption)
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.getOrElse(sand)
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if finalPosition == sand || finalPosition.y >= lowestLevel then None
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else Some(Grid(blocks + ((finalPosition, Block.Sand))))
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end Grid
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val grid: Grid =
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input
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.flatMap(
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_.split(" -> ")
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.map(_.split(",")).map { case Array(x, y) => (x.toInt, y.toInt) }.sliding(2).flatMap {
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case Array((x1, y1), (x2, y2)) =>
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if x2 - x1 == 0 then
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for y <- y1 to y2 by (Math.signum(y2 - y1).toInt) yield ((x2, y), Block.Rock)
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else for x <- x1 to x2 by (Math.signum(x2 - x1).toInt) yield ((x, y2), Block.Rock)
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}
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)
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.toMap
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.pipe(Grid.apply)
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val part1 = LazyList
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.iterate(Option(grid))(_.flatMap(_.dropSand((500, 0))))
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.takeWhile(_.isDefined)
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.map(_.get)
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println("Part 1:")
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println(part1.last.show)
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println(part1.length - 1)
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val grid2 = Grid(
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grid.blocks ++ (
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for x <- 300 to 700
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yield ((x, grid.lowestLevel + 2), Block.Rock)
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)
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)
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val part2 = LazyList
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.iterate(Option(grid2))(_.flatMap(_.dropSand((500, 0))))
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.takeWhile(_.exists(_.blocksWithDefault(500, 0) != Block.Sand))
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.map(_.get)
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println("Part 2:")
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println(part2.last.show)
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println(part2.length)
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end Day14
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