说明：  数据结构二叉树实现代码：功能如下： （1）创建二叉树 （2）递归算法先序遍历二叉树 （3）非递归算法中序遍历二叉树 （4）递归算法后序遍历二叉树 （5）求二叉树叶子结点个数 （6）按层次遍历二叉树 （7）求二叉树树深
(A binary tree data structure to achieve the code: Function is as follows: (1) Create a binary tree (2) recursive algorithm for preorder traversal binary tree (3) non-recursive algorithm for binary tree inorder traversal (4) recursive algorithm for postorder 2 tree (5) Find the number of binary tree leaf nodes (6) according to the level binary tree traversal (7) Find the binary tree depth)