1) 用先序递归过程建立二叉树（存储结构：二叉链表）

输入数据按先序遍历所得序列输入，当某节点左子树或右子树为空时，输入‘*’号，如输入abc**d**e**

2) 编写递归算法，计算二叉树中叶子结点的数目。

3）按凹入表方式输出该二叉树。

-1) The process established by the first order recursive binary tree (memory structure: binary list) input data sequence obtained by first traversing the input, when a node in the left subtree or right subtree is empty, enter ' *'　number, such as Enter abc** d** e** 2) write a recursive algorithm to calculate a binary tree the number of leaf nodes. 3) The concave form by way of the output of the binary tree.