aoc2023/Day2.scala

package aoc.day2

import aoc._

case class Hand(red: Int, green: Int, blue: Int):
  def max(other: Hand) =
    Hand(red max other.red, green max other.green, blue max other.blue)
  def power = red * green * blue
case class Game(id: Int, hands: List[Hand]):
  def power =
    hands.foldLeft(Hand(0, 0, 0))(_ max _).power

object Parser extends CommonParser:
  val update =
    num.into: num =>
      "red" ^^^ ((h: Hand) => h.copy(red = num)) |
        "green" ^^^ ((h: Hand) => h.copy(green = num)) |
        "blue" ^^^ ((h: Hand) => h.copy(blue = num))
  val hand = rep1sep(update, ",").map(_.foldRight(Hand(0, 0, 0))(_(_)))

  val game = "Game" ~ num ~ ":" ~ repsep(hand, ";") ^^ { case (_ ~ num ~ _ ~ hands) =>
    Game(num, hands)
  }
end Parser

// Part 1

def getGames = lines.map(Parser.parse(Parser.game, _).get)

def part1 =
  val games = getGames.toList
  val res =
    games
      .filter(g => g.hands.forall(h => h.red <= 12 && h.green <= 13 && h.blue <= 14))
      .map(_.id)
      .sum
  println(res)

def part2 =
  val res = getGames.map(_.power).sum
  println(res)

@main def Day2(part: Int) = part match
  case 1 => part1
  case 2 => part2