sumew · April 14, 2020 02:52
diff --git a/preOrder.scala b/preOrder.scala
 def preOrder[T,S](tree: Tree[T], f: T => S): Queue[S] = {
  def loop(g: Tree[T], output: Queue[S]): Queue[S] = g match {
    case Tree(v,c) =>   c.foldLeft(output.enqueue(f(v))){case (acc,n) => loop(n,acc)}
  }
  loop(tree,Queue.empty[S])
 }
	def preOrder[T,S](tree: Tree[T], f: T => S): Queue[S] = {
	def loop(g: Tree[T], output: Queue[S]): Queue[S] = g match {
	case Tree(v,c) => c.foldLeft(output.enqueue(f(v))){case (acc,n) => loop(n,acc)}
	}
	loop(tree,Queue.empty[S])
	}