线性dp：关于树的数量（线性dp类型）

How many trees?

题面翻译

用n个点组成二叉树，问高度大于等于h的有多少个。

题目描述

In an ancient text file contained profound knowledge. The profound wisdom within this file was so deep that even Phong, the oldest resident of Mainframe couldn’t understand it. Despite this he managed to glean some insights. For example he learned that User launches games for leisurely enjoyment leading to catastrophic Game Cubes falling onto cities where modules fail to defeat them.

Certainly, after Guard Bob's appearance in Mainframe, many modules ceased to fear Game Cubes. If Bob, being alive still, has never lost to User an