真二叉树重构

代码说明：

  但是对于“真二叉树”（每个内部节点都有两个孩子的二叉树），给定它的先序、后序遍历序列足以完全确定它的结构。将二叉树的n个节点用[1, n]内的整数进行编号，输入一棵真二叉树的先序、后序遍历序列，请输出它的中序遍历序列。(But for one proper binary tree, in which each internal node has two sons, we can uniquely determine it through its given preorder traversal sequence and postorder traversal sequence.Label n nodes in one binary tree using the integers in [1, n], we would like to output the inorder traversal sequence of a binary tree through its preorder and postorder traversal sequence.)