如何在scala中创建列表中的元素组合

object CombinationGenerator {
  def main(args: Array[String]): Unit = {
    val list = List(1, 2, 3, 4)
    val combinations = generateCombinations(list)
    combinations.foreach(println)
  }

  def generateCombinations[A](list: List[A]): List[List[A]] = {
    def combine(remaining: List[A], current: List[A]): List[List[A]] = remaining match {
      case Nil => List(current)
      case head :: tail =>
        val withHead = combine(tail, current :+ head)
        val withoutHead = combine(tail, current)
        withHead ++ withoutHead
    }

    combine(list, Nil)
  }
}

def generateCombinationsIterative[A](list: List[A]): List[List[A]] = {
  val result = scala.collection.mutable.ListBuffer[List[A]]()
  result += List.empty[A]

  for (elem <- list) {
    val currentSize = result.size
    for (i <- 0 until currentSize) {
      val currentCombination = result(i)
      result += currentCombination :+ elem
    }
  }

  result.toList
}