The Great Tree-List Recursion Problem.
Asked by Varun Bhatia.
Write a recursive function treeToList(Node root) that takes an ordered binary tree and rearranges the internal pointers to make a circular doubly linked list out of the tree nodes. The”previous” pointers should be stored in the “small” field and the “next” pointers should be stored in the “large” field. The list should be arranged so that the nodes are in increasing order. Return the head pointer to the new list.
This is very well explained and implemented at: Convert a Binary Tree to a Circular Doubly Link List