确定二叉树的特征。如：每个节点的层次，从根到该节点的枝长（路径长度），子孙的个数及祖先的个数。每个节点在前序、中序、后序中的访问的序号。-To determine the characteristics of a binary tree. Such as: the level of each node from the root to the node branch length (path length), the number of children and grandchildren an