easyDSA

Longest consecutive sequence in O(n) with hash set — why not sort?

Q: Longest consecutive sequence in O(n) with hash set — why not sort?

**Core concept.** Longest consecutive sequence in O(n) with hash set is a classic interview signal. Input n steps Optimal O(n log n) Result Verified How it works — use optimal structure, maintain invariants, handle empty/single/duplicate. Brute O(n²) vs optimal O(n) or O(n log n). | | Brute | Optimal | |---|---|---| | Time

142 views

Understand the problem

Explain approach, complexity, and edge cases. Provide complexity table and visual steps.

hash setarrayMeta

Attempt it yourself

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

Nudge consolestandby

Stuck? Beam a request up — the console returns a conceptual nudge that guides your logic without spoiling the implementation.

Study the solution

Core concept. Longest consecutive sequence in O(n) with hash set is a classic interview signal.

Solution ready — 2 min read

Classified // press E to declassify

Join the discussion

Discussion (0)

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

Transmission complete // awaiting log

KEEP THE
STREAK ALIVE.

Dossier 24 of 127 decoded in the Data Structures & Algorithms track. One more won't hurt.

Back to track

Next up→

How do you find a duplicate in an array?

Continue