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Doubly linked list advantages and disadvantages

Short answer

A doubly linked list node has prev and next pointers, enabling two-way traversal. Advantages: O(1) deletion of a known node, easy insertion before/after a node, support for undo/redo. Disadvantages: extra memory per node, more pointer updates making code complex, slightly slower operations than singly list.

Define a doubly linked list with its advantages and disadvantages.

A doubly linked list is a linked list in which every node has two pointers: prev to the previous node and next to the next node, besides the data field. The first node's prev and last node's next are NULL.

NULL<-[ |10| ]<->[ |20| ]<->[ |30| ]->NULL

Advantages

  • Traversal in both forward and backward directions.
  • A node can be deleted directly when only its address is known; no trailing pointer is needed.
  • Insertion before a given node is easy.
  • Useful for undo/redo, browser history, music players.

Disadvantages

  • Extra memory for the second pointer in every node.
  • More pointers (two or four) must be changed on each insertion/deletion, so code is more complex and error-prone.
  • Operations are slightly slower than in a singly linked list doing the same job.
  • No random access, same as any linked list.

✓ Answer checked by Claude Opus 5.5 (high effort)

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