Definition

A Doubly Linked List is a data structure where each node holds data plus two pointers: prev (to the previous node) and next (to the next node). Unlike a singly linked list that can only move forward via next, it can traverse in both directions.

Key Characteristics

• ✓Bidirectional pointers: Each node is [prev | data | next], allowing movement both ways.
• ✓Reverse traversal: Can scan backward from tail via prev — impossible in a singly linked list.
• ✓O(1) deletion: Given a reference to the node, link its neighbors directly via prev/next to delete in O(1).
• ✓Extra memory: Each node needs an additional prev pointer, using slightly more memory than singly linked.

Time Complexity