feat(2024/14): 2024 day 14

Author: scarf005

2024/day14.scala

@@ -0,0 +1,82 @@
+package `2024`.day14
+
+import prelude.*
+import java.awt.image.BufferedImage
+import com.sksamuel.scrimage.ImmutableImage
+import com.sksamuel.scrimage.webp.WebpWriter
+
+given size: Size = Size(101, 103)
+
+case class Robot(p: Pos, v: Pos):
+  def at(t: Int)(using size: Size): Pos =
+    val x = {
+      val x = (p.x + t * v.x) % size.width
+      if x < 0 then size.width + x else x
+    }
+    val y = {
+      val y = (p.y + t * v.y) % size.height
+      if y < 0 then size.height + y else y
+    }
+    Pos(x, y)
+
+object I:
+  def unapply(s: String): Option[Int] = s.toIntOption
+
+def parse(input: String) =
+  input
+    .split("\n")
+    .toSeq
+    .collect { case s"p=${I(x)},${I(y)} v=${I(vx)},${I(vy)}" =>
+      Robot(Pos(x, y), Pos(vx, vy))
+    }
+
+enum Quadrant:
+  case I, II, III, IV
+
+def quadrant(p: Pos)(using size: Size): Option[Quadrant] =
+  ((p.x - size.width / 2).sign, (p.y - size.height / 2).sign) match
+    case (1, 1)   => Some(Quadrant.I)
+    case (-1, 1)  => Some(Quadrant.II)
+    case (-1, -1) => Some(Quadrant.III)
+    case (1, -1)  => Some(Quadrant.IV)
+    case _        => None
+
+def asImage(xs: Set[Pos])(using size: Size) =
+  val image = BufferedImage(size.width, size.height, BufferedImage.TYPE_INT_RGB)
+  val g = image.createGraphics()
+  for
+    x <- 0 until size.width
+    y <- 0 until size.height
+  do
+    g.setColor(
+      if xs(Pos(x, y)) then java.awt.Color.BLACK else java.awt.Color.WHITE,
+    )
+    g.fillRect(x, y, 1, 1)
+  g.dispose()
+
+  image
+
+def part1(input: String) =
+  val robots = parse(input)
+  robots.map(_.at(100)).flatMap(quadrant).frequencies.values.reduce(_ * _)
+
+def part2(input: String) =
+  val robots = parse(input)
+
+  for t <- 6470 until 6480 do
+    val pos = robots.map(_.at(t)).toSet
+
+    ImmutableImage
+      .fromAwt(asImage(pos))
+      .output(
+        WebpWriter.MAX_LOSSLESS_COMPRESSION,
+        f"img/2024/14/$t%05d.webp",
+      )
+
+@main def main =
+  val input = fromFile(".cache/2024/14.txt").mkString
+
+  println(part1(input))
+
+  os.makeDir.all(os.pwd / "img" / "2024" / "14")
+  println(part2(input))

README.md

@@ -22,6 +22,8 @@ $ scala-cli test .
 
 ## Images
 
-|               2015 Day6 Part 1                |                2015 Day6 Part 2                 |
-| :-------------------------------------------: | :---------------------------------------------: |
-| ![2015 Day6 Part 1](img/2015/day6.part1.webp) | ![2015 Day6 Part 2](./img/2015/day6.part2.webp) |
+|           2015 Day6 Part 1            |           2015 Day6 Part 2           |
+| :-----------------------------------: | :----------------------------------: |
+| <img width="100%" src="img/2015/day6.part1.webp">  | <img width="100%" src="img/2015/day6.part2.webp"> |
+|         **2024 Day14 part 2**         |                                      |
+| <img width="100%" src="img/2024/day14.part2.webp"> |                                      |