package tree object Size { def size[A](t: Tree[A]): Int = t match { case Leaf(_) => 1 case Branch(l, r) => 1 + size(l) + size(r) } 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(size(tree)) } }
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