What is the difference between a singly linked list and a doubly linked list?

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What is the difference between a singly linked list and a doubly linked list?

A singly linked list and a doubly linked list are two different types of data structures used to store and manipulate collections of elements. The main difference between them lies in the way they store and maintain the connections between the elements.

1. Singly Linked List:
A singly linked list is a linear data structure where each element, known as a node, contains a value and a reference to the next node in the list. The last node in the list points to null, indicating the end of the list. The key characteristics of a singly linked list are as follows:

- Each node contains a value and a reference to the next node.
- Traversing the list can only be done in a forward direction.
- Insertion and deletion of elements can be done efficiently at the beginning or end of the list.
- Searching for a specific element requires traversing the list from the beginning.

2. Doubly Linked List:
A doubly linked list is also a linear data structure, but each node contains a value, a reference to the next node, and a reference to the previous node. The first node's previous reference and the last node's next reference point to null. The key characteristics of a doubly linked list are as follows:

- Each node contains a value, a reference to the next node, and a reference to the previous node.
- Traversing the list can be done in both forward and backward directions.
- Insertion and deletion of elements can be done efficiently at any position in the list.
- Searching for a specific element can be done in both forward and backward directions.

In summary, the main difference between a singly linked list and a doubly linked list is the presence of the previous node reference in the doubly linked list. This additional reference allows for more flexibility in traversing the list and performing operations such as insertion and deletion at any position. However, the doubly linked list requires more memory to store the additional references compared to the singly linked list.