Linked List

Implement a doubly linked list.

Like an array, a linked list is a simple linear data structure. Several common data types can be implemented using linked lists, like queues, stacks, and associative arrays.

A linked list is a collection of data elements called nodes. In a singly linked list each node holds a value and a link to the next node. In a doubly linked list each node also holds a link to the previous node.

You will write an implementation of a doubly linked list. Implement a Node to hold a value and pointers to the next and previous nodes. Then implement a List which holds references to the first and last node and offers an array-like interface for adding and removing items:

• push (insert value at back);
• pop (remove value at back);
• shift (remove value at front).
• unshift (insert value at front);

To keep your implementation simple, the tests will not cover error conditions. Specifically: pop or shift will never be called on an empty list.

If you want to know more about linked lists, check Wikipedia.

Running the tests

You can run all the tests for an exercise by entering

$ gradle test

in your terminal.

Source

Classic computer science topic

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.