若在二叉链表的结点中只增设一个双亲域 以指示其双亲结点，则在遍历过程中能否不设栈？ 试以此存储结构编写不设栈进行中序遍历的递推形 式的算法。-If the binary node list only the addition of a parent domain to indicate their parent node, then traverse the process can not stack? Try to store the structure of the prepar