先创建一个二叉树，然后进行中序遍历，输出节点内容，之后对二叉树叶子节点进行计数，从而实现对二叉树的基本操作！-First create a binary tree, and then in-order traversal, the contents of the output node, and then count the leaf nodes of the binary tree in order to achieve the basic operation of a binary tree!