feat(2024): day 25

Author: scarf005

2024/day25.scala

@@ -0,0 +1,31 @@
+package `2024`.day25
+
+import prelude.*
+
+enum Scheme(xs: Vector[Int]):
+  case Lock(xs: Vector[Int]) extends Scheme(xs)
+  case Key(xs: Vector[Int]) extends Scheme(xs)
+
+export Scheme.*
+
+extension (l: Lock)
+  inline infix def isMatching(k: Key)(using height: Int): Boolean =
+    (l.xs zip k.xs).forall((x, y) => x + y <= height)
+
+def parse(input: String): Scheme =
+  val lines = input.split('\n').toVector.transpose
+  val xs = lines.map(_.count(_ == '#'))
+  if lines.head.head == '#' then Lock(xs) else Key(xs)
+
+@main def main() =
+  val input = fromFile(".cache/2024/25.txt").mkString.trim
+  val xs = input.split("\n\n").toVector
+
+  given height: Int = xs.head.linesIterator.size
+
+  val (locks, keys) = xs.map(parse).partitionMap {
+    case lock: Lock => Left(lock)
+    case key: Key   => Right(key)
+  }
+  val combos = locks.flatMap(l => keys.filter(l.isMatching))
+  println(combos.size)