jaenwawe / phase-4-data-structures-reverse-doubly-linked-list

Reverse a Doubly Linked List

Learning Goals

• Build a doubly linked list and use it to solve an algorithm

Introduction

At this point we've learned how to solve algorithms with singly linked lists, and learned what doubly linked lists are, so it's time to put that knowledge to use and solve an algorithm with a doubly linked list!

Fork and clone this lab; you'll be coding in the lib folder. You can run the tests at any point using learn test to check your work.

Instructions

Write a method LinkedList#reverse! that reverses the list in place, so the head is the new tail, the tail is the new head, and all of the prev_node and next_node attributes of each node in the list point to the correct nodes.

For example:

• Input: 6 <--> 7 <--> 8

• Output: 8 <--> 7 <--> 6

• Input: 11 <--> 18 <--> 19 <--> 94

• Output: 94 <--> 19 <--> 18 <--> 11

• Input: 41 <--> 101 <--> 8 <--> 28 <--> 32

• Output: 32 <--> 28 <--> 8 <--> 101 <--> 41

Bonus

Try to solve the problem recursively!

Hint: You might want to create a recursive helper method reverse_node instead of trying to use the reverse! method recursively.