增强二叉搜索树是二叉搜索树的一种推广，其中每个结点除了保存关键字外，还保存了以该结点为根的子树的结点数目（包括该结点本身）。实现其建立、复制、前/中/后序遍历、层高统计、结构从属判断等操作。-Enhanced binary search tree is a generalization of a binary search tree, where each node except to save the keyword, but also save the node number points to the node is the root of the subtree (including the node itself). Achieve its create, copy, before/during/after preorder, statistics storey structure subordinate judges and other operations.