# Which Data Structure Is Implemented Doubly Linked List?

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Larry Thompson

A doubly linked list is a type of data structure that allows traversal in both forward and backward directions. It is implemented using nodes that contain references to the previous and next nodes in the list. In this article, we will explore the implementation of a doubly linked list and understand its advantages and use cases.

## Implementation of Doubly Linked List

To implement a doubly linked list, we start by defining a class for the nodes. Each node contains three components:

• Data: This represents the value stored in the node.
• Previous: This is a reference to the previous node in the list.
• Next: This is a reference to the next node in the list.

We can represent these components using instance variables within our class:

```class Node {
T data;
Node previous;
Node next;
}
```

The ‘T’ represents the generic type of data that can be stored in each node. For example, if we want to create a doubly linked list of integers, we would replace ‘T’ with ‘int’.

The main advantage of using a doubly linked list over other data structures like arrays or singly linked lists is its ability to efficiently traverse both forward and backward. The ‘previous’ reference allows us to easily access elements before a given node, while the ‘next’ reference allows us to access elements after it.

This flexibility makes doubly linked lists ideal for certain operations such as inserting or deleting elements at any position within the list. Unlike singly linked lists, which require traversing from the beginning of the list to reach a specific position, doubly linked lists allow us to start from either end and traverse in the desired direction.

## Use Cases of Doubly Linked List

Doubly linked lists are commonly used in scenarios where we need efficient insertion and deletion operations at both ends of the list. Some common use cases include:

• Deque: A deque (double-ended queue) is a data structure that allows insertion and deletion at both ends. It can be efficiently implemented using a doubly linked list as it provides constant time complexity for these operations.
• Undo/Redo functionality: Applications that require undo/redo functionality often utilize doubly linked lists to keep track of previous states and easily navigate between them.
• Caches: Doubly linked lists can be used to implement caches, where the most recently accessed elements are stored at the front of the list for quick retrieval.

### In conclusion,

Doubly linked lists provide a flexible and efficient way to store and manipulate data. With their ability to traverse in both forward and backward directions, they offer advantages over other data structures in certain use cases. By understanding their implementation and advantages, you can leverage doubly linked lists effectively in your own programs.