ByteDance Interview Questions — Page 15

ByteDance·Machine Learning Engineer·Technical Phone Screen

May 2026

Bytedance ML engineer interview that went deep into LLM internals. Three topics back to back, all technical, no fluff. The kind of session where you either know the math or you don't.

Walk through how Flash Attention works, including the tiling mechanism and why it reduces memory bandwidth overhead.
Explain KV Cache: what gets stored, how memory usage scales, and what trade-offs come with it during autoregressive decoding.
Describe how RoPE encodes position information and why rotating query and key vectors achieves relative position awareness.

“I knew the high-level pitch but stumbled when they pushed on the tiling math specifically.”

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ByteDance·Data Scientist·Online Assessment (OA)

May 2026

Bytedance Data Scientist online assessment with three coding problems. Nothing behavioral, just straight algorithmic stuff. The problems ranged from trivially easy to genuinely tricky depending on how you think about segment maintenance.

Given a string, treat uppercase and lowercase as identical. Count how many adjacent pairs of characters differ from each other.
Implement a memory allocator that only starts allocations at indices divisible by 8. Support alloc(x) to find the leftmost valid free block and assign it an ID, and erase(id) to free all cells belonging to that ID.
Points on a number line can be colored one at a time. After each update (assign or change a color), return the total number of maximal contiguous same-color segments. Design an efficient online approach.

“Easiest of the three.”

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ByteDance·Software Engineer·Technical Phone Screen

May 2026

Bytedance SWE interview with an in-place array problem. Pretty standard algorithmic round but the two-pointer constraint made it trickier than it looked at first glance.

Given a sorted integer array, remove duplicates in-place so each unique element appears at most twice. Return the count of remaining elements. Must be O(n) time and O(1) space.

“The two-pointer setup clicked pretty fast for me.”

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ByteDance·Software Engineer·Technical Phone Screen

May 2026

Bytedance SWE interview with a tricky binary search problem that looks straightforward until you actually have to implement the counting step under pressure.

Given an integer array of length n and an integer k, find the kth smallest subarray sum.

“I knew binary search on the answer was the right direction pretty fast, but the part that tripped me up was implementing the two-pointer count of subarrays with sum at or below the midpoint.”

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ByteDance·Software Engineer·Technical Phone Screen

May 2026

Bytedance SWE coding round with a DP problem that looked like a simple greedy at first but definitely wasn't. The question had enough edge cases to make you second-guess yourself the whole way through.

You start at position 0 and need to deliver cargo to a target position T by walking forward. There are charging stations at sorted positions along the way, and at any station you can launch a drone that carries the cargo exactly 10 units forward (no walking cost for that segment). Compute the minimum total walking distance to deliver the cargo to T.

“My first instinct was pure greedy, just launch the drone at every station you pass and call it done.”

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ByteDance·Software Engineer·Onsite - Behavioral / Leadership

May 2026

Behavioral round at Bytedance for a software engineer role, basically a full walkthrough of your resume with a lot of follow-up pressure on the details. They want specifics, not summaries.

Walk me through a significant project on your resume: what was the context, what did you specifically contribute, and what were the outcomes?
What technical trade-offs did you make during that project, and what alternatives did you consider?
Looking back, what would you do differently on that project?
What did you learn from the challenges you faced in that role?

“This is the core of the whole interview.”

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ByteDance·Software Engineer·Onsite - Coding / Algorithms

May 2026

Bytedance coding round for a Software Engineer role. Two algorithm problems, both leaning toward the harder side of what you'd expect for this kind of screen.

Given a list of closed intervals, merge all overlapping ones and return a sorted list of non-overlapping intervals.
Given an array of bar heights in a histogram, find the maximum rectangular area you can form using one or more consecutive bars.

“Classic problem but I fumbled the edge case where one interval completely swallows the next.”

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ByteDance·Software Engineer·Technical Phone Screen

May 2026

Bytedance software engineer interview with a parsing/evaluation problem that looked straightforward but had a lot of edge cases packed in. The kind of question where you think you're done and then they keep asking 'what about this input'.

Write a function that validates and evaluates an arithmetic expression string containing only non-negative integers and the operators + and -. The function should reject invalid inputs (leading zeros, adjacent operators, operator at start or end, invalid characters, numbers or result outside 32-bit signed integer range) and return the computed result for valid ones.

“I started coding before I fully thought through the validation rules and it bit me.”

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ByteDance·Machine Learning Engineer·Technical Phone Screen

May 2026

Bytedance ML engineer interview with a meaty NLP question about semantic similarity. One question, two approaches, lots of pseudocode. The kind of problem that feels manageable until they start asking about edge cases.

Implement a function to compute semantic similarity between two text snippets. Walk through at least two approaches (e.g. sentence encoders vs. averaged word embeddings), compare their quality and compute trade-offs, and cover edge cases like very short texts, OOV tokens, and punctuation handling. Pseudocode is fine if time is short.

“I went with sentence encoders first since that felt like the stronger answer, encode both texts with something like Sentence-BERT and take cosine similarity of the two vectors.”

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ByteDance·Data Scientist·Technical Phone Screen

May 2026

Bytedance Data Scientist interview with a coding-heavy session that escalated from stack design to streaming statistics to tree problems. The progression felt deliberate, like each question was trying to build on the last, which was an interesting structure but also kind of exhausting.

Design a stack that supports push, pop, top, and getMin, where all operations run in O(1) time.
Design a stack that also supports peekMax (return the current max without removing it) and popMax (remove and return the maximum element), with efficient time complexity.
Design a data structure that supports adding numbers from a stream one at a time and returning the current median after each insertion. Also discuss whether the MaxStack design idea can be adapted here.
Given a binary tree with integer values, determine if there exists a path that sums to a target value, where the path can start at any node, moves only upward toward ancestors, and must be a contiguous chain of nodes (no branching, no revisiting).

“Classic warmup.”

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