ピクロス（お絵かきロジック）を解くプログラム

solvepicross.scala

object Main extends App {

  def possibleSeq(baseSeq: Seq[Option[Boolean]]): Seq[Seq[Boolean]] =
    baseSeq.foldLeft(Seq(Seq.empty[Boolean])) { (acc, ele) =>
      ele match {
        case Some(b) => acc.map(_ ++ Seq(b))
        case None => acc.flatMap(s => Seq(s ++ Seq(true), s ++ Seq(false)))
      }
    }

  def reduceSeq(possibleSeqs: Seq[Seq[Boolean]]): Seq[Option[Boolean]] = {
    possibleSeqs.tail.foldLeft(possibleSeqs.head.map(Some(_)): Seq[Option[Boolean]]) { (acc, ele) =>
      acc.zip(ele).iterator.map {
        case (a, b) if (a.contains(b)) => a
        case _ => None
      }.toSeq
    }
  }

  def serialize(seq: Seq[Boolean]): Seq[Int] =
    seq.foldLeft((0, Seq.empty[Int])) { (acc, ele) =>
      ele match {
        case true => (acc._1 + 1, acc._2)
        case false if acc._1 > 0 => (0, acc._2 ++ Seq(acc._1))
        case _ => acc
      }
    } match {
      case (0, res) => res
      case (las, res) => res ++ Seq(las)
    }

  def checkValid(seq: Seq[Boolean], nums: Seq[Int]): Boolean = {
    serialize(seq) == nums
  }

  def rowUpdate(table: Seq[Seq[Option[Boolean]]]) =
    table.zip(rowNums).map { tpl =>
      reduceSeq(possibleSeq(tpl._1).filter(checkValid(_, tpl._2)))
    }

  def colUpdate(table: Seq[Seq[Option[Boolean]]]) =
    table.transpose.zip(colNums).map { tpl =>
      reduceSeq(possibleSeq(tpl._1).filter(checkValid(_, tpl._2)))
    }.transpose

  def doIter(table: Seq[Seq[Option[Boolean]]]) = colUpdate(rowUpdate(table))

  def printout(res: Seq[Seq[Option[Boolean]]]): Unit = {
    res.foreach(row =>
      println(row.map {
        case Some(true) => "■"
        case Some(false) => "□"
        case None => "◆"
      }.mkString(""))
    )
  }

  // サンプルデータ
  val totalSize = 10
  val rowNums = Seq(
    Seq(4),
    Seq(3, 1),
    Seq(1, 2),
    Seq(5, 1),
    Seq(1, 1),
    Seq(1, 3),
    Seq(3, 4),
    Seq(4, 4),
    Seq(4, 2),
    Seq(2)
  )
  val colNums = Seq(
    Seq(2),
    Seq(4),
    Seq(4),
    Seq(8),
    Seq(1, 1),
    Seq(1, 1),
    Seq(1, 1, 2),
    Seq(1, 1, 4),
    Seq(1, 1, 4),
    Seq(8)
  )
  val table: Seq[Seq[Option[Boolean]]] = (1 to totalSize).map(_ =>
    (1 to totalSize).map(_ => None))

  // 計算・出力
  val t1 = doIter(table)
  val t2 = doIter(t1)
  val t3 = doIter(t2)
  printout(t1)
  println("")
  printout(t2)
  println("")
  printout(t3)

}