Day 2

aoc/src/Day2.scala

@@ -0,0 +1,54 @@
+import scala.io.Source
+object Day2 extends App:
+  enum Move:
+    case Forward(distance: Int) extends Move
+    case Down(distance: Int) extends Move
+    case Up(distance: Int) extends Move
+
+  import Move._
+
+  val moves = Source
+    .fromURL(getClass.getResource("day2Input.txt"))
+    .mkString
+    .split('\n')
+    .toList
+    .map(_.split(' '))
+    .map {
+      case Array("forward", distance) => Forward(distance.toInt)
+      case Array("down", distance)    => Down(distance.toInt)
+      case Array("up", distance)      => Up(distance.toInt)
+    }
+
+  case class SimplePosition(horizontal: Int, depth: Int) {
+    def performMove(move: Move): SimplePosition = move match {
+      case Forward(distance) =>
+        SimplePosition(horizontal + distance, depth)
+      case Up(distance) =>
+        SimplePosition(horizontal, depth - distance)
+      case Down(distance) =>
+        SimplePosition(horizontal, depth + distance)
+    }
+  }
+
+  val finalPositionPart1 =
+    moves.foldLeft(SimplePosition(0, 0))(_.performMove(_))
+  println(
+    s"Part 1: ${finalPositionPart1.depth * finalPositionPart1.horizontal}"
+  )
+
+  case class BetterPosition(aim: Int, horizontal: Int, depth: Int) {
+    def performMove(move: Move): BetterPosition = move match {
+      case Forward(distance) =>
+        BetterPosition(aim, horizontal + distance, depth + aim * distance)
+      case Up(distance) =>
+        this.copy(aim - distance)
+      case Down(distance) =>
+        this.copy(aim + distance)
+    }
+  }
+
+  val finalPositionPart2 =
+    moves.foldLeft(BetterPosition(0, 0, 0))(_.performMove(_))
+  println(
+    s"Part 2: ${finalPositionPart2.depth * finalPositionPart2.horizontal}"
+  )