package tree object DepthByFold { def depth[A](t: Tree[A]): Int = Fold.fold(t)(_ => 0)((a, b) => (a max b) + 1) def main(args: Array[String]): Unit = { val tree = Branch(Leaf(1), Branch(Branch(Branch(Leaf(3), Branch(Leaf(5), Leaf(6))), Leaf(4)), Leaf(2))) println(depth(tree)) } }
5
原文：http://www.cnblogs.com/JonkeyGuan/p/5424836.html