TODO.txt

List of todo difficult or important questions:

### Reverse a doubly linked list
https://www.hackerrank.com/challenges/reverse-a-doubly-linked-list/problem?filter=java8&filter_on=language&h_l=interview&page=1&playlist_slugs%5B%5D%5B%5D=interview-preparation-kit&playlist_slugs%5B%5D%5B%5D=linked-lists


### Inserting a Node Into a Sorted Doubly Linked List
https://www.hackerrank.com/challenges/insert-a-node-into-a-sorted-doubly-linked-list/problem?h_l=interview&playlist_slugs%5B%5D%5B%5D=interview-preparation-kit&playlist_slugs%5B%5D%5B%5D=linked-lists
 1. Empty list
 2. At the beginning of the list
 3. Somewhere at the middle of the list
 4. At the end of the list