Is it possible to efficiently determine the tail element of a doubly linked list without a full traversal?

A doubly linked list usually has references to the next and previous elements. If you only have a pointer to an arbitrary element in the list, it is impossible to determine the tail (last element) without traversing the list, since references only go to neighboring elements.

However, if the list structure is implemented with a reference to the tail (for example, in a list class), then access to the last element will be efficient (O(1)).

In summary: without an additional reference to the tail or traversing the list, it is impossible to determine the last element.