feat(2024/19): day 19

2024/day19.scala

@@ -0,0 +1,24 @@
+package `2024`.day19
+
+import scala.collection.concurrent.TrieMap
+import scala.annotation.tailrec
+import prelude.*
+
+case class Towel(val designs: Set[String]):
+  def combos(str: String): Long =
+    val memo = TrieMap[String, Long]("" -> 1)
+
+    def go(left: String): Long = memo.getOrElseUpdate(
+      left,
+      designs.view.filter(left.startsWith).sumBy { p => go(left.drop(p.size)) },
+    )
+    go(str)
+
+@main def main =
+  val input = fromFile(".cache/2024/19.txt").getLines
+  val (towel, cases) = input.splitAt(2) |> ((a, b) =>
+    (a.mkString.split(",").map(_.trim).toSet |> Towel.apply, b.toVector)
+  )
+  val result = cases.map(towel.combos)
+  println(s"part1: ${result.count(_ > 0)}")
+  println(s"part2: ${result.sum}")

2024/day19.test.scala

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+package `2024`.day19
+
+import munit.FunSuite
+
+class Test extends FunSuite:
+  test("example"):
+    val towel = Towel(Set("r", "wr", "b", "g", "bwu", "rb", "gb", "br"))
+
+    val cases = Map[String, Long](
+      "brwrr" -> 2,
+      "bggr" -> 1,
+      "gbbr" -> 4,
+      "rrbgbr" -> 6,
+      "ubwu" -> 0,
+      "bwurrg" -> 1,
+      "brgr" -> 2,
+      "bbrgwb" -> 0,
+    )
+    cases.foreach((a, b) => assertEquals(towel.combos(a), b))