LinkedIn Senior SDE — 5 Rounds + Extra HM, Offered

Timeline

• All rounds completed over ~2 weeks
• After final round: told feedback was positive but original team was filled
• Extra HM round scheduled same day with different team
• Selected same day after the extra HM round

Round 1 — Phone Screen (45 min)

Started with resume/project discussion, then moved to technical:

Q1: Simple Rate Limiter Implementation

• Interviewer asked: "How would you implement a simple rate limiter?"
• Discussed token bucket and sliding window approaches
• Talked through trade-offs and where each is appropriate

Q2: 2D Matrix Problem

• Don't remember the exact problem (matrix-based coding question)
• Standard medium difficulty

Round 2 — Hiring Manager (45 min)

Standard HM round:

• Projects I've worked on and my ownership in them
• Technical decisions and their reasoning
• Behavioral questions (conflict resolution, driving impact)
• Situational/leadership scenarios

No coding. Pure conversation about engineering judgment and culture fit.

Round 3 — Coding & Algorithms (60 min, CoderPad)

Q1: Max Consecutive Ones III

• Given binary array and k flips allowed, find longest subarray of 1s
• Used sliding window approach — solved completely

Follow-up: What if the array is circular? Discussed adapting the window to handle wrap-around (double the array or use modular indexing).

Q2 (Bonus — 30 min remaining): Course Schedule II Variant

• Topological sort / Kahn's algorithm
• Explained the approach fully
• Ran out of time for complete implementation — wrote pseudocode instead

Round 4 — Coding with AI Assist (60 min, CoderPad)

Unique round — boilerplate code and test cases provided, plus an AI-assist tab available.

Problem: Adjacency list representing friendships between users.

Part 1: Find shortest path between two users (return full path)

• BFS with parent tracking

Part 2: Find shortest distance between users

• Reused BFS logic from Part 1, modified to return distance

Part 3: Suggest friends based on mutual connections

• For a given user, find users who share the most mutual friends but aren't directly connected

Completed all 3 parts with passing test cases.

What the interviewer evaluated:

• Code reusability (how I built Part 2 and 3 on top of Part 1)
• How I structured code as requirements evolved incrementally
• How I used AI assistance (not blindly accepting — validating, checking edge cases)
• Whether I was critically reviewing AI-generated code

Key insight: LinkedIn's "Coding with AI" round isn't about avoiding AI — it's about demonstrating you can USE AI effectively while maintaining engineering judgment.

Round 5 — System Design & Architecture (60 min)

Problem: Design a Top-N leaderboard of most-shared articles on LinkedIn over rolling windows of 5 minutes, 1 hour, and 24 hours.

Covered:

• Event ingestion (article share events via Kafka)
• Rolling window computation (sliding window counters vs time-bucketed aggregation)
• Storage for different window sizes (Redis sorted sets for real-time, pre-computed for larger windows)
• Read path optimization (cache the leaderboard, refresh periodically)
• Scaling for LinkedIn's volume (millions of shares/day)
• Accuracy vs latency trade-offs (approximate counts at scale)

The Team Switch

After design round: recruiter said feedback was positive across all rounds. BUT — the original team had already filled its opening while I was interviewing.

Recruiter quickly found another HM with an open position. Extra HM round was scheduled same day — behavioral + team-fit discussion. Selected that day.

Lesson: Positive interview feedback at LinkedIn doesn't guarantee an offer on the team you interviewed for. Teams fill roles in parallel. But if your feedback is strong, they'll find you a match quickly.

Tips for LinkedIn Senior SDE

1. "Coding with AI" round is real — don't fight it. Use the AI tab, but validate everything it generates. They're testing your judgment + collaboration with AI tools.
2. Reusability matters — they give multi-part problems specifically to see if you build incrementally or rewrite from scratch each time.
3. System design is LinkedIn-specific — expect feed ranking, leaderboards, notification systems, connection graphs. Know how these work at scale.
4. Phone screen is lighter — don't over-prepare for it. Medium difficulty at most.
5. Team matching happens fast — if you get positive feedback, they actively find you a team. Don't panic if the original team is filled.
6. Pseudocode is acceptable if time runs out — but explain the full approach verbally.