6th Chapter Clue Two fork Tree

A pointer to a precursor and a successor is called a Clue, and a two-linked list of clues is called a clue list, and the corresponding two-fork tree is called the Clue Two fork tree (threaded binary trees).

The essence of the clue is to change the null pointer of the two-fork list to a precursor or a subsequent clue. Because the precursor and the subsequent information can only be obtained when traversing the two-fork tree, the process of the clue is the process of modifying the null pointer during the traversal.

6th Chapter Clue Two fork Tree