Wondering what the Snapchat Online Assessment (OA) looks like — and how to prepare for it without guessing? You’re in the right place. Snapchat’s coding screen blends classic DSA with platform-flavored problems: rolling windows, TTLs, caches, graphs, and event streams. If you want to show up confident and ready, this guide gives you the structure and the specifics.

When to Expect the OA for Your Role

Snapchat’s OA timing and format depends on your role and level. Here’s what candidates commonly see:

• New Grad & Interns – Expect an OA invite within a week or two of recruiter contact. For many, it’s the primary technical screen before final rounds.
• Backend / Full-Stack / Mobile – Standard practice. You’ll likely receive a HackerRank or CodeSignal link with 2–3 timed questions. Questions lean on arrays, hashing, graphs, and sliding window.
• Data / ML / Computer Vision – Still an OA, but may include matrix operations, probabilities, or stream processing (think counters, histograms, simple transforms).
• SRE / Infra / Data Platform – OA may feature log parsing, rate limiting, metrics aggregation, or queue/consumer logic.
• Senior & Staff – Some candidates skip a generic OA and go straight to live coding or design, but many still see an OA as a first pass.

Action step: Ask your recruiter which platform (HackerRank, CodeSignal, etc.), duration, number of questions, and supported languages (Snap commonly uses Python, Java, C++, Kotlin, Swift).

Does Your Online Assessment Matter?

Short answer: absolutely.

• It’s the main filter. A strong resume gets the invite; your OA performance gets you the loop.
• It sets the tone. Interviewers may review your OA solutions and probe your decisions later.
• It mirrors Snap problems. Expect time-based windows, TTLs, content ranking, and high-volume event handling.
• It signals how you work. Clarity, tests, naming, and edge-case handling all count.

Pro tip: Treat the OA like your first interview. Write clean code, explain edge cases in comments, and aim for both correctness and readability.

Compiled List of Snapchat OA Question Types

Practice these categories and you’ll cover most of what Snap throws at you:

1. Longest Substring with At Most K Distinct Characters — Sliding Window / Hash Map
2. Time-Based Key-Value Store — Map + Binary Search / TTL-adjacent patterns
3. Design Hit Counter — Queues / Rolling Window
4. Logger Rate Limiter — Hashing / Time Buckets
5. Top K Frequent Elements — Heap / Bucket Sort
6. LRU Cache — LinkedHashMap / Doubly Linked List + Hash Map
7. Video Stitching — Interval Cover / Greedy
8. Meeting Rooms II — Intervals / Min-Heap
9. Clone Graph — Graph / DFS-BFS
10. Number of Provinces — Graph / Union-Find
11. K Closest Points to Origin — Heap / Geometry
12. Design Underground System — Hash Maps / Aggregation
13. Minimum Window Substring — Sliding Window
14. Encode and Decode Strings — String Serialization
15. Binary Search on Answer (e.g., Capacity to Ship Packages) — Greedy + Binary Search

How to Prepare and Pass the Snapchat Online Assessment

Think of this as training camp: build reflexes, not just memory.

1. Assess Your Starting Point (Week 1)

• Take 1–2 timed problems in your preferred language (Python/Java/C++/Kotlin/Swift).
• Score yourself on arrays, hashes, graphs, heaps, intervals, and sliding windows.
• Identify two weak areas to target first (e.g., graphs + intervals).

2. Pick a Structured Learning Path (Weeks 2-6)

• Self-study on LeetCode/HackerRank
• Best for autonomy. Use Explore cards and curated lists.
• Mock assessments
• Timed, proctored sessions simulate real OA stress.
• Mentor or career coach
• A software engineer career coach can tighten pacing, reviews, and communication.

3. Practice With Realistic Problems (Weeks 3-8)

• Build a 40–60 problem set covering: sliding window, intervals, heaps, graphs, caches, time-based data.
• Always timebox (60–90 minutes for 2–3 problems), then refactor for clarity afterward.
• Alternate topics to avoid tunnel vision.

4. Learn Snapchat-Specific Patterns

Expect questions flavored by Snap’s products (Stories, Spotlight, Maps):

• Ephemeral data with TTLs (expiration, cleanup, queries by time)
• Rolling windows and rate limiting (spam prevention, abuse throttling)
• Media metadata and intervals (stitching, scheduling, dedup)
• Ranking/aggregation (top-K, counters, deduplication at scale)
• Graphs (mutual friends, traversal, connected components)
• Location proximity (grid bucketing, KNN, geospatial simplifications)

5. Simulate the OA Environment

• Use the same editor and language you’ll use in the OA.
• Run two full simulations: 75–90 minutes, 2–3 medium-level problems.
• Practice I/O quirks, reading constraints, and writing small test drivers.

6. Get Feedback and Iterate

• Track mistakes: off-by-one in windows, missed null/empty cases, slow I/O.
• Re-solve missed problems 3–7 days later from scratch.
• Share solutions for review or compare against top LeetCode discuss posts.

Snapchat Interview Question Breakdown

Here are featured sample problems that mirror Snapchat-style assessments. Work through these patterns under time.

1. Time-Based Key-Value Store with TTL

• Type: Hash Map + Binary Search / Sliding Window
• Prompt: Implement a set/get(key, value, timestamp) store where values expire after T seconds. get returns the latest non-expired value at a given query time.
• Trick: Maintain a sorted list of (timestamp, value) per key; binary search by query time; lazily purge expired entries or check expiry at read time.
• What It Tests: Time-indexed data modeling, binary search, edge cases for expiration and missing keys.

2. Logger Rate Limiter with Burst Control

• Type: Hash Map / Queue / Rolling Window
• Prompt: Given a stream of user events, allow up to N events per user in any rolling W-second window. Return which events are allowed.
• Trick: For each user, store event timestamps in a deque; pop from the left while outside window; allow if size < N.
• What It Tests: Sliding window under load, per-entity state, amortized O(1) maintenance.

3. Mutual Friends and Friend-of-Friend Suggestions

• Type: Graph / BFS / Counting
• Prompt: Given an undirected friendship graph and a user u, suggest top K users at distance 2 sorted by number of mutual friends (ties by ID).
• Trick: BFS from u to distance 2; count mutuals via adjacency intersection or increments; exclude existing friends and u.
• What It Tests: Graph traversal, counting/aggregation, careful filtering.

4. Video Story Stitching

• Type: Intervals / Greedy
• Prompt: You’re given clips [start, end] and a target duration T. Find the minimum number of clips to cover [0, T], or return -1.
• Trick: Sort by start; greedily extend the farthest reachable end within the current range; count jumps when you move the window.
• What It Tests: Interval coverage, greedy reasoning, sorting and scanning.

5. Top-K Trending Lenses in a Rolling Window

• Type: Heap / Hash Map / Sliding Window
• Prompt: Given (timestamp, lensId) events, return top K lensIds for each second in a rolling W-second window.
• Trick: Maintain counts in a hash map + min-heap of size K; decrement as events fall out of window (secondary deque per second or buckets).
• What It Tests: Streaming aggregation, window maintenance, top-K with churn.

What Comes After the Online Assessment

Passing the OA is step one. Here’s what typically follows.

1. Recruiter Debrief & Scheduling

Expect an email within a few days. You’ll get high-level feedback and a schedule for live interviews. Ask about formats (pair programming vs. whiteboard), languages, and any role-specific focus areas.

2. Live Technical Interviews

You’ll collaborate with Snapchat engineers via a shared editor (e.g., CoderPad/CodePair).

• Algorithms & Data Structures (interactive)
• Debugging or refactoring a small codebase
• Mobile roles may get Kotlin/Swift coding or platform APIs (sans heavy framework)

Pro tip: Revisit your OA code. Interviewers may ask you to walk through decisions or improve them.

3. System Design / Architecture Round

For mid-level+ roles, expect a design session. Examples:

• Ephemeral messaging service with TTL and read receipts
• Stories/Spotlight feed generation and ranking
• Rate limiting and abuse prevention service
• Media upload pipeline with CDN and thumbnail caching

They’ll evaluate scale, consistency, failure modes, storage choices, and clarity of trade-offs.

4. Behavioral & Values Interviews

Snap emphasizes collaborative, product-minded engineering. Expect prompts like:

• “Tell me about a time you shipped under tight constraints.”
• “Describe a disagreement and how you resolved it.”
• “How did you balance user privacy and product goals?”

Use STAR. Highlight kindness, clear communication, creativity, and ownership.

5. Final Round / Virtual Onsite

A multi-interview block that may include:

• Another coding round (fresh problem)
• Systems/architecture deep dive
• Cross-functional chat with PM or data partners

Plan for context switching and pacing across several hours.

6. Offer & Negotiation

Comp offers typically include base, bonus, and equity. Do market research for location bands and be ready to negotiate on level, scope, and start date.

Conclusion

You don’t need to guess. You need a plan. If you:

• Diagnose weak spots early,
• Drill Snapchat-style patterns under time,
• Write clean, tested code with edge cases in mind,

you’ll turn the Snapchat OA from a hurdle into your opening. The problems are tough but predictable. Prepare like it’s your first interview — because it is — and you’ll walk into the next stages ready to execute.

For more practical insights and prep strategies, explore the Lodely Blog or start from Lodely’s homepage to find guides and career resources tailored to software engineers.