Problem
Given a doubly linked list of n elements. Your task is to reverse the doubly linked list in-place.
Example 1:
Input:
LinkedList: 3 <--> 4 <--> 5
Output: 5 4 3
Example 2:
Input:
LinkedList: 75 <--> 122 <--> 59 <--> 196
Output: 196 59 122 75...
