线索二叉树 建立中序线索二叉树，并且中序遍历 求中序线索二叉树上已知结点中序的前驱和后继-Binary tree in order to establish clues clues tree, and in the traversal sequence for clues in the binary tree nodes on the known sequence of the precursor and follow-up

由双亲表示法建立3棵树，将这些树表示的森林转换成二叉树，对二叉树进行线索化并遍历。-Law established by the parents said three trees, these trees will be converted into a binary representation of the forest for clues and binary tree traversal.