The Great Tree-List Recursion Problem

This an advanced problem that uses pointers, binary trees, linked lists, and some significant recursion. The pointer to the topmost node in a tree is called the “root”. The circular doubly linked list is a standard linked list with two additional features…

The single node in a length-1 list is both the first and last node, so its pointers point to itself.

Source: cslibrary.stanford.edu