如何在Scala中用FP实现广度优先搜索

case class Node(name: String, neighbors: List[Node] = List.empty)

import scala.annotation.tailrec

def bfs(start: Node): List[String] = {
  @tailrec
  def bfsHelper(queue: List[Node], visited: Set[Node], result: List[String]): List[String] = {
    if (queue.isEmpty) {
      result
    } else {
      val current = queue.head
      val unvisitedNeighbors = current.neighbors.filterNot(visited.contains)
      val newQueue = queue.tail ++ unvisitedNeighbors
      val newVisited = visited ++ unvisitedNeighbors
      val newResult = result :+ current.name
      bfsHelper(newQueue, newVisited, newResult)
    }
  }
  
  bfsHelper(List(start), Set(start), List.empty)
}

val nodeA = Node("A")
val nodeB = Node("B")
val nodeC = Node("C")
val nodeD = Node("D")
val nodeE = Node("E")
val nodeF = Node("F")

nodeA.neighbors = List(nodeB, nodeC)
nodeB.neighbors = List(nodeD, nodeE)
nodeC.neighbors = List(nodeF)

val result = bfs(nodeA)
println(result)