What is a doubly linked list, and how does it work?

A doubly linked list is a type of data structure where each node contains a data part and two pointers, pointing to the previous and next node.

In more detail, a doubly linked list is a more complex type of linked list which contains a pointer to the next as well as the previous node in the sequence. This means that it consists of nodes and each node has three fields: data, a pointer to the next node, and a pointer to the previous node. The data field is used to store the data. The next pointer points to the next node in the list and the previous pointer points to the previous node in the list.

The first node of the doubly linked list has its previous pointer pointing to null, indicating it's the start of the list, and the last node has its next pointer pointing to null, indicating it's the end of the list. This allows traversal in both directions, from the start to the end, and vice versa, which is not possible in a simple linked list.

The doubly linked list provides a greater flexibility compared to a singly linked list. It can be traversed in both forward and backward direction. In addition, with a doubly linked list, you can delete a given node more efficiently if the node is given. This is because in a singly linked list, to delete a node, pointer to the previous node is needed, but we can get the previous node using the previous pointer in a doubly linked list.

However, the main drawback of a doubly linked list is that it requires more space for each node and operations like insertion, deletion, and traversal are more complex due to the additional previous pointer.

In summary, a doubly linked list is a type of data structure that allows bidirectional traversal. Each node contains a data part and two pointers, pointing to the previous and next node, providing greater flexibility but at the cost of increased complexity and space.