more scala

2022/day2-v2.scala

@@ -0,0 +1,39 @@
+import scala.io.Source
+import scala.math.floorMod
+
+enum RPS(val score: Int):
+	case Rock     extends RPS(1)
+	case Paper    extends RPS(2)
+	case Scissors extends RPS(3)
+
+	def +(amount: Int) = RPS.fromOrdinal(floorMod(ordinal + amount, 3))
+	def -(amount: Int) = RPS.fromOrdinal(floorMod(ordinal - amount, 3))
+	def -(other: RPS) = score - other.score
+
+	def vs(other: RPS) = floorMod(this - other, 3) match
+		case 1 => 6
+		case 2 => 0
+		case _ => 3
+
+val moveMap = Map("A"->RPS.Rock, "B"->RPS.Paper, "C"->RPS.Scissors, "X"->RPS.Rock, "Y"->RPS.Paper, "Z"->RPS.Scissors)
+
+@main def main() =
+	val strategyGuide = Source.fromFile("day2-input").getLines.map(_.split(" ")).toArray  // Can't leave it lazy as Part 1 will consume it
+	// val strategyGuide = Source.fromString("A Y\nB X\nC Z\n").getLines.map(_.split(" ")).toArray
+
+	// Part 1 - evaluate all moves in the guide using moveMap and tally score
+	println(strategyGuide.map(movePair=>
+		val theirMove = moveMap(movePair(0))
+		val ourMove = moveMap(movePair(1))
+		ourMove.score + (ourMove vs theirMove)
+	).sum)
+
+	// Part 2 - X->lose, Y->draw, Z->win
+	println(strategyGuide.map(movePair=>
+		val theirMove = moveMap(movePair(0))
+		val ourMove = movePair(1) match
+			case "X" => theirMove - 1
+			case "Y" => theirMove
+			case "Z" => theirMove + 1
+		ourMove.score + (ourMove vs theirMove)
+	).sum)