1、（实习题） 请编写一个程序，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。-1, (practice questions) Write a program to determine the characteristics of a binary tree. Such as: the level of each node, the node from the root to shoot length (