Advent of Code Day 6 part 1 in Scala

advent_day_6_pt1.scala

import scala.io.Source

object App {

  case class CommandLine(command: String,
                         leftTop: (Int, Int),
                         rightBottom: (Int, Int))

  case object CommandLine {
    def fromString(s: String): CommandLine = {
      val preProcessed = s.replace("turn off", "turn-off")
        .replace("turn on", "turn-on")
        .split(' ')
      val command = preProcessed(0)
      val leftTopString = preProcessed(1)
      val rightBottomString = preProcessed(3)

      def parseCoordinates(s: String): (Int, Int) = {
        val pairsString = s.split(',')
        (pairsString(0).toInt, pairsString(1).toInt)
      }
      CommandLine(command, parseCoordinates(leftTopString), parseCoordinates(rightBottomString))
    }
  }

  class Grid(grid: Array[Array[Int]]) {
    def updateGrid(c: CommandLine): Unit = {
      val (x1, y1) = c.leftTop
      val (x2, y2) = c.rightBottom
      for (x <- x1 to x2) {
        val row = grid(x)
        for (y <- y1 to y2) {
          c.command match {
            case "turn-off" => grid(x)(y) = -1
            case "turn-on" => grid(x)(y) = 1
            case "toggle" => grid(x)(y) = grid(x)(y) * -1
          }
        }
      }
    }

    def countLights: Int = {
      grid.flatten.count((e) => e == 1)
    }
  }

  def main(args: Array[String]) = {
    val lines = Source.fromFile("input.txt").getLines()
    val grid = new Grid(Array.tabulate(1000, 1000)((x, y) => -1))
    for (line <- lines) {
      val command = CommandLine.fromString(line)
      grid.updateGrid(command)
    }
    println(grid.countLights)
  }

}