Находит все перестановки в матрице

MatrixPermutations.scala

object MatrixPermutations {

  def main(args: Array[String]): Unit = {
    val in = List(
      List(1,2),
      List(3,4),
      List(5,6),
    )

    def findAllPermutations[T](matrix: List[List[T]]): List[List[T]] = {
      matrix match {
        case Nil => Nil
        case head :: tail =>
          findAllPermutations(tail) match {
            case Nil =>
              head.map { elem =>
                elem :: Nil
              }
            case tailPermutations =>
              tailPermutations.flatMap { tailPermutation =>
                head.map { elem =>
                  elem +: tailPermutation
                }
              }
          }
      }
    }

    val res = findAllPermutations(in)
    println(res) // List(List(1, 3, 5), List(2, 3, 5), List(1, 4, 5), List(2, 4, 5), List(1, 3, 6), List(2, 3, 6), List(1, 4, 6), List(2, 4, 6))
  }
}