Bytedance·Machine Learning Engineer·Technical Phone Screen·Intermediate

Intermediate

Jun 2026

Summary

Bytedance ML engineer screen, one coding question, pretty standard stuff. They went straight to algorithms without much small talk.

Questions Asked (1)

Given an array of integers, find the contiguous subarray with the largest sum and return that sum.

Algorithms & Data Structures

Author's notes

Classic Kadane's algorithm.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem constraints (e.g., array size, possible negative numbers) and then propose Kadane's algorithm, which scans the array once while tracking the maximum sum ending at the current position and the overall maximum. Walk through a small example to demonstrate correctness, then analyze time and space complexity.

Pro tip: Mention that Kadane's algorithm can be adapted to return the actual subarray indices if needed, and discuss how to handle edge cases like all-negative arrays by initializing with the first element rather than zero.

1. Clarify requirements and constraints

Ask about input size, whether the array can be empty, and if negative numbers are allowed. Confirm the expected return type (sum only or subarray).

2. Propose an efficient algorithm

Introduce Kadane's algorithm: iterate through the array, maintaining the maximum sum of a subarray ending at the current index, and update the global maximum.

3. Walk through an example

Use a small array (e.g., [-2,1,-3,4,-1,2,1,-5,4]) to show how the algorithm works step by step, highlighting the decisions at each index.

4. Analyze complexity and edge cases

State that the time complexity is O(n) and space is O(1). Discuss edge cases: empty array, all negatives, single element, and how to handle them.

5. Discuss extensions and trade-offs

Mention how to modify the algorithm to return the subarray itself, and compare with a divide-and-conquer approach (O(n log n)) if asked.

Key Points to Mention

Kadane's algorithm and its dynamic programming foundation
Time complexity O(n) and space complexity O(1)
Handling all-negative arrays by initializing with the first element
The importance of clarifying constraints and edge cases before coding
How to track subarray boundaries if the actual subarray is required
Alternative approaches like divide-and-conquer and their trade-offs

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.