Contents

object SpiralMatrix {

  type Matrix = Seq[Seq[Int]]
  type Point = (Int, Int)

  def spiralMatrix(dim: Int): Matrix = {
    val spiralPoints =
      (for {
        start <- startPoints(dim)
        squareSize = dim - start._1 * 2
      } yield squarePoints(squareSize, start)).flatten.distinct

    toMatrix(dim, spiralPoints zip Stream.from(1))
  }

  private def startPoints(dim: Int): Seq[Point] =
    (0 to math.ceil(dim / 2d).toInt) map (x => (x, x))

  private def squarePoints(squareSize: Int, start: Point): Seq[Point] = {
    def translate(p: Point): Point = (p._1 + start._1, p._2 + start._2)
    def toPoint(f: Int => Point)(x: Int) = translate(f(x))
    def side(f: Int => Point, reversed: Boolean = false): Seq[Point] = {
      val result = (0 until squareSize) map toPoint(f)
      if (reversed) result.reverse else result
    }

    if (squareSize <= 0) List()
    else if (squareSize == 1) List(start)
    else {
      val maxCoord = squareSize - 1

      val top    = side((_, 0))
      val right  = side((maxCoord, _))
      val bottom = side((_, maxCoord), reversed = true)
      val left   = side((0, _), reversed = true)

      (top ++ right ++ bottom ++ left).distinct
    }
  }

  private def toMatrix(dim: Int, data: Seq[((Int, Int), Int)]): Matrix = {
    val matrix = Array.ofDim[Int](dim, dim)
    data foreach { case ((x, y), n) =>
      matrix(y)(x) = n
    }
    matrix map (_.toSeq) toSeq
  }
}

Version data entries

188 entries across 188 versions & 1 rubygems

Version	Path
trackler-2.2.1.180	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.179	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.178	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.177	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.176	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.175	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.174	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.173	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.172	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.171	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.170	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.169	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.167	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.166	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.165	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.164	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.163	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.162	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.161	tracks/scala/exercises/spiral-matrix/example.scala
trackler-2.2.1.160	tracks/scala/exercises/spiral-matrix/example.scala