What is the time complexity of doubly linked list?

Best case O(1) insert/delete given the node. Worst case O(n) search. Space complexity is O(n).

Doubly linked list

easy

In a singly linked list you cannot delete a node you are standing on - you need its predecessor. A prev pointer removes that walk, which is why LRU caches and browser history use this structure.

Best O(1) insert/delete given the nodeWorst O(n) searchSpace O(n)

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Where to go next

Singly linked list

easy

O(1) at the head, a walk for everything else.

LRU cache

hard

A hash map and a doubly linked list, covering each other's weakness.

Deque

medium

A queue open at both ends.