Part2 4.6

DiagramArea.scala

import scala.io.StdIn

object Main extends App {
  val input = StdIn.readLine()
  val heights = input.foldLeft(Seq(0)) { case (hs, x) =>
    val add = x match {
      case '\\' => hs.last - 1
      case '/' => hs.last + 1
      case '_' => hs.last
    }
    hs :+ add
  }

  def calcArea(heights: Seq[Int]): Int = {
    val surface = math.min(heights.head, heights.last)
    heights.filter(_ < surface).map(surface - _).sum
  }

  val builder = List.newBuilder[Int]
  var fst = 0
  val areas = heights.map { h =>
    builder += h
    if(fst <= h) {
      val hs = builder.result
      println(hs)
      builder.clear
      builder += h
      fst = h
      calcArea(hs)
    } else 0
  } :+ calcArea(builder.result)

  println(areas.filter(_ != 0))
}