线索二叉树，二叉树的中序线索化方法。建立二叉树对应的二叉链表，先将该二叉树线索化，然后用非栈非递归方式输出该二叉树的中序序列。采用二叉链表存储结构，用递归方式

-Threaded Binary Tree, inorder threaded binary tree method. The establishment of the corresponding binary tree binary list, the first clue of the binary tree, and then use the output of non-stack non-recursive manner in order of the binary tree sequence. List storage structure using two forks, using recursive method