如何从Scala中的项目列表中获取n个项目的组合？

import scala.collection.mutable.ListBuffer

def getCombinations(projects: List[String], n: Int): List[List[String]] = {
  val combinations = ListBuffer[List[String]]()
  
  def backtrack(start: Int, currentCombination: List[String]): Unit = {
    if (currentCombination.length == n) {
      combinations.append(currentCombination)
    } else {
      for (i <- start until projects.length) {
        backtrack(i + 1, currentCombination :+ projects(i))
      }
    }
  }
  
  backtrack(0, List[String]())
  combinations.toList
}

val projects = List("Project1", "Project2", "Project3", "Project4")
val n = 2

val combinations = getCombinations(projects, n)
combinations.foreach(println)

List(Project1, Project2)
List(Project1, Project3)
List(Project1, Project4)
List(Project2, Project3)
List(Project2, Project4)
List(Project3, Project4)