topic
The following forest into a corresponding binary tree, and threaded respectively following instructions:
(1) first order precursor threaded;
(2) the whole sequence and subsequent clue clue clue of precursors;
(3) subsequent successor threaded.
thought
The first question of the precursor of FIG related cues
while drawing whole binary clues, the dotted line is a pointer to the node precursor, the solid line to the successor.
answer
