Matrix rotation

Rotation.scala

object Rotation extends App {

  val matrix = Array(Array(1,2), Array(3,4), Array(5,6))
  print(matrix)

  print(transpose(matrix))
  print(rotate90(matrix))
  print(rotateMinus90(matrix))

  def transpose(matrix: Array[Array[Int]]): Array[Array[Int]] = {
    matrix.head.indices.map(i => matrix.map(_(i))).toArray
  }

  def rotate90(matrix: Array[Array[Int]]): Array[Array[Int]] = {
    transpose(matrix).map(_.reverse)
  }

  def rotateMinus90(matrix: Array[Array[Int]]): Array[Array[Int]] = {
    val t = transpose(matrix)
    t.head.indices.foreach { i =>
      (0 until (t.length/2)).foreach { j =>
        val temp = t(j)(i)
        t(j)(i) = t(t.length - j - 1)(i)
        t(t.length - j - 1)(i) = temp
      }
    }
    t
  }

  def print(matrix: Array[Array[Int]]): Unit = {
    matrix.foreach(r => println(r.mkString(" ")))
    println()
  }
}

I was trying to solve this problem from Cracking coding interview book and your solution is very easy and logical. But I have two questions

• Function rotate90 could you expand the (_) to be a full expression? And why not you use transpose function in scala direct?
• Function rotateMinus90 Can we change that to be more functional why without for loop?