Introduction - If you have any usage issues, please Google them yourself
Generate a two fork tree BT (no less than 15 nodes) stored with a two chain list.
2) the BT is traversed with the preorder of recursive and non recursive methods, and the information of each node on BT is printed in the form of contraction.
3) write the algorithm, exchange the left and right subtrees of all nodes on the BT, and print out the BT node information before and after the exchange in the form of the contraction.