hardDSA

How does an LRU cache work internally?

Q: How does an LRU cache work internally?

An **LRU (Least-Recently-Used) cache** must do three things in **O(1)**: look up by key, mark an entry as just-used, and evict the **least-recently-used** entry when full. The standard design combines **two structures**: a **hash map** (key → node) for O(1) lookup, and a **doubly-linked list** ordered by recency (most-recent at the front, least-recent at the back): hash map key → node O(1) find <text class='d-accent d-sub' x='180' y='34' te

710 views

Understand the problem

Hash map plus linked list.

lru-cachedata-structures

Attempt it yourself

Sketch your approach before reading the solution — that's what interviews test.

Stuck? AI Nudge Available

Get a conceptual hint to guide your logic without spoiling the final implementation.

Study the solution

The solution is waiting

Give it an honest attempt first — then compare your thinking with the full walkthrough.

Run the code

PYAn LRU cache via OrderedDict

Practice

Join the discussion

Discussion (0)

No responses yet. Be the first to share what you think.

How does CPython execute your code?

What is a deadlock in Python?