ByteDance interview notes, page 21 of 29

FAANG / Big Tech

Most of these ByteDance write-ups come from Software Engineers (194), then Machine Learning Engineers (45) and Data Scientists (17). The most reported rounds are the technical phone screen (227), the system design round (28), the behavioral / leadership round (16) and the onsite coding round (9).

289 interview notes · updated Sep 2026

ByteDance·Backend Engineer·Technical Phone Screen

Jun 2026

Backend engineer interview at Bytedance that touched on prompt engineering, which I wasn't expecting to prep for at all. Not a ton of detail to share but the question itself was interesting enough to write up.

What techniques do you use when writing prompts? Specifically: how do you describe prompts when working with a coding agent, and how do you design prompt templates?

“They basically split the question into two parts themselves, which helped me not ramble.”

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ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance Data Engineer interview with a dynamic programming problem on video subsequences. The follow-up added a fixed-count repetition twist that I wasn't fully prepared for.

You have an array of video durations and a user attention limit A. Select a subsequence of videos (preserving original order) such that every pair of adjacent selected videos has a combined duration at most A, and the total watch time is maximized. What's your approach?
Follow-up: if the user can rewatch videos (repetitions allowed) but must watch exactly m videos total, how do you modify the approach to maximize total watch time under the same adjacency constraint?

“Took me a minute to realize this is a DP problem.”

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ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance SWE interview with a graph/union-find style problem. Pretty standard stuff for a big tech coding round, though the transitive similarity angle made me think harder than I expected.

Given n photos and an n x n binary matrix indicating which photos are directly similar, find the total number of photo groups, where similarity is transitive (if A is similar to B and B is similar to C, then A and C are in the same group).

“Classic connected components problem dressed up with a photo theme.”

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ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance SWE coding round, one BFS problem the whole time. I hadn't interviewed in ages and it showed. The interviewer was patient but I fumbled through the logic and needed a bunch of hints before we moved on.

You have two cups of sizes x and y and unlimited water. You can fill a cup, empty a cup, or pour from one into the other. Can you measure exactly z units of water, and if so, what is the minimum number of operations to get there?

“Classic water jug BFS and I still botched it.”

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ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance coding round, one problem that's basically a harder version of Number of Islands. Manageable if you've done the prep, but the rotation/reflection part is where people get tripped up.

Given a 2D grid with multiple islands, determine how many distinct island shapes exist, where two islands are considered the same shape if one can be translated, rotated, or reflected to match the other.

“The basic translation-only version I had down cold.”

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ByteDance·Data Scientist·Technical Phone Screen

Jun 2026

SQL round for a Data Scientist role at Bytedance. One question, medium difficulty, and the interviewer nudged me about duplicates partway through which I probably should've caught myself.

Write a SQL query to find the total number of distinct users who both registered and published at least one post on the same day. Keep in mind a user can publish multiple posts in a single day.

“The interviewer had to remind me about duplicates, which was a bit embarrassing.”

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ByteDance·Data Analyst·Technical Phone Screen

Jun 2026

Bytedance Data Analyst technical screen, two SQL problems back to back. Nothing behavioral, just pure query writing under a bit of time pressure. The problems weren't impossible but the details tripped me up more than I expected.

Given a users table and a transactions table, identify users whose total completed crypto transaction amount exceeded £100 within the 7 days following their account creation. Return the user ID and that summed amount.
Using an activity table that logs views and clicks per product, compute the click-through rate for each product and return whichever product (or products) has the highest CTR. Exclude any product that has zero views.

“The window join is where I fumbled a bit.”

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ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance SWE interview with a trie-based design question. Pretty standard algorithmic round but the wildcard search part trips people up if they haven't thought through the recursion carefully.

Design a data structure that supports adding words and searching for them, where the search pattern can include '.' as a wildcard that matches any single character.

“I jumped straight to trie and felt good about addWord, but the search with '.' took me longer than I'd like to admit.”

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ByteDance·Software Engineer·Technical Phone Screen

Jun 2026

Bytedance SWE interview with a graph/union-find problem that sounds straightforward until you actually sit down to code it under pressure.

Given an n x n binary matrix, you can flip at most one 0 to a 1. What is the size of the largest 4-directionally connected island you can form after doing so?

“I went straight for BFS to label each island and track sizes, then scanned for zeros and checked neighboring island labels to sum up potential merges.”

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ByteDance·Software Engineer·Onsite - System Design / Architecture

Jun 2026

System design round at Bytedance for a software engineer role, focused entirely on building a content moderation platform for a short-video product. The scope was massive and I don't think I fully covered everything they were looking for, but it was a genuinely interesting problem.

Design a large-scale content moderation system for a short-video platform that handles video, captions, comments, audio, and metadata, and can detect violations like spam, nudity, violence, hate speech, self-harm, and copyright issues, with both pre-publish and post-publish checks.

“This is a beast of a question.”

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