Snap interview notes, page 8 of 22

Large Enterprises

Most of these Snap write-ups come from Software Engineers (117), then Machine Learning Engineers (65) and Data Scientists (18). The most reported rounds are the technical phone screen (149), the system design round (45), the behavioral / leadership round (11) and the product sense round (8).

216 interview notes · updated Jul 2026

Snap·Software Engineer·Technical Phone Screen

May 2026

Snapchat SWE interview with a data structures design question that had more depth to it than I expected. The trade-off discussion is where they really wanted to see your thinking.

Design a data structure that supports two operations: one that records a strictly increasing integer timestamp, and one that returns how many recorded timestamps are strictly greater than a given value. Then discuss the trade-offs between different designs that optimize for different access patterns.

“I went straight for the obvious approach, store timestamps in a list, binary search on query, O(1) write and O(log n) read.”

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Snap·Software Engineer·Technical Phone Screen

May 2026

Snapchat software engineer interview with a mix of classic LeetCode problems spanning math, graph traversal, data structures, and streaming algorithms. Nothing too exotic but the range was wide enough to keep you on your toes.

Given a deck of cards represented as integers, determine whether you can split the deck into groups of X cards where every group has the same number.
Given a 2D grid with islands, count the number of distinct island shapes where two islands are considered the same if one can be translated to match the other.
Implement a Trie data structure that supports inserting words, searching for exact words, and checking if any word starts with a given prefix.
Design a data structure that supports adding numbers from a stream and querying the median at any point in time.

“The GCD angle took me a minute to see.”

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Snap·Machine Learning Engineer·Technical Phone Screen

May 2026

Snapchat ML Engineer interview with a coding round that did not go well. The question was a classic graph problem and I fumbled the implementation badly enough that there's not much else to say.

Given a number of courses and a list of prerequisites, determine whether it's possible to complete all courses without getting stuck in a dependency cycle.

“Went straight for DFS and fell apart on the visited state logic.”

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Snap·Software Engineer·Technical Phone Screen

May 2026

Snapchat software engineering interview with a pretty gnarly string compression problem. One question, but it had enough layers to keep me busy for the whole session.

Given a string, compress it by replacing consecutive repeated substrings with a count and pattern notation, where patterns can be nested recursively. Implement a function that returns the shortest possible encoding, or the original string if no encoding is shorter. Walk through how you detect repeated structure, handle nested encodings, avoid redundant computation, and analyze time and space complexity.

“This one hurt a little.”

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Snap·Data Scientist·Technical Phone Screen

May 2026

Stats and ML round for a DS role at Snapchat, centered on building a predictive model end to end. The questions were more conceptual than I expected, mixing practical modeling workflow with some math and theory.

Walk through how you would build a predictive model for a product metric, from defining the target variable and features all the way through evaluation and iteration.
Write out the logistic function mathematically and explain why it works well for binary classification.
In Random Forests, what exactly is random, and why does introducing that randomness actually help?

“This felt broad enough that I wasn't sure where to start.”

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Snap·Machine Learning Engineer·Onsite - System Design / Architecture

May 2026

ML system design round at Snapchat, two big open-ended questions back to back. Both were the kind where you could talk for an hour and still feel like you left stuff on the table.

Walk through an ML system you know well, covering problem framing, data sources, feature generation, training pipeline, inference path, model refresh strategy, monitoring, and the trade-offs between offline and online components.
Design a ranking system for a personalized feed, search results, or recommendations surface. Cover the objective function, candidate generation, ranking model, feature store, training data, serving stack, latency budget, experimentation plan, and how you'd handle cold start, exploration vs exploitation, feedback loops, and model drift.

“I picked a ranking system I'd worked on and immediately went too deep into the feature engineering part.”

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Snap·Software Engineer·Technical Phone Screen

May 2026

Snapchat backend interview that basically came down to graph traversal. The problem was well-scoped but the follow-up discussion on edge cases is where things got interesting.

Given a set of services with directed dependencies and a latency value on each edge, find the minimum latency path between a start service and an end service. Then discuss how you'd handle disconnected graphs, zero-latency edges, cycles, and what the time complexity looks like.

“I jumped straight to Dijkstra with a priority queue and that part went fine.”

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Snap·Software Engineer·Onsite - System Design / Architecture

May 2026

Snapchat system design round, one big open-ended question about building a metrics and alerting platform from scratch. Felt like a pretty senior-leaning prompt and I spent a lot of time second-guessing my storage choices.

Design an end-to-end metrics collection and alerting system that supports high write throughput, near real-time dashboards, long-range historical queries, and user-defined alerting rules across many services and hosts.

“This one sprawled fast.”

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Snap·Software Engineer·Technical Phone Screen

May 2026

Snapchat software engineer interview with a sliding window problem that looked manageable until it really wasn't. The median part is what gets you.

Given an array of numbers and a window size k, compute the median of each window as it slides from left to right across the array.

“I knew what a sliding window was, sure, but maintaining a running median as elements enter and leave the window is a completely different problem.”

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Snap·Software Engineer·Technical Phone Screen

May 2026

Snapchat software engineering interview with a Swift concurrency question that looks deceptively simple until you actually have to explain it out loud.

In Swift, predict the print output and order for this code snippet using two async dispatches on the main queue, and explain why the second closure prints '123' instead of '13' even though String is a value type.

“This one got me.”

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