Bytedance·Software Engineer·Technical Phone Screen·Intermediate

IntermediatePrefer not to say

May 2026Remote

Summary

Bytedance software engineer phone screen, one coding question that was basically a sliding window variant. The interviewer seemed less sharp than expected, which honestly made the whole thing feel a bit anticlimactic.

Questions Asked (1)

You have a row of candies, each with a type. You can only collect two distinct types at a time, and once you pick a candy you must also take the one adjacent to it. If you hit a third type, you stop. Find the maximum number of candies you can collect.

Algorithms & Data Structures

Author's notes

Classic sliding window once you see it, but the 'must take the adjacent one' constraint threw me for a second.

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AI HintsAI Generated

Suggested Approach

Clarify the problem constraints and then propose a sliding window approach that maintains at most two distinct candy types. Explain how to expand the window and shrink it when a third type appears, tracking the maximum length.

Pro tip: Mention that this is equivalent to the 'Fruit Into Baskets' problem and that the optimal solution runs in O(n) time with O(1) space, demonstrating pattern recognition and efficiency.

1. Clarify the problem

Restate the problem in your own words and ask clarifying questions about input format, constraints, and edge cases (e.g., empty row, all same type).

2. Identify the pattern

Recognize that the problem reduces to finding the longest contiguous subarray with at most two distinct values, which is a classic sliding window problem.

3. Design the algorithm

Use two pointers (left and right) to represent the window. Expand right, add the new type to a frequency map, and while the map size exceeds 2, shrink from left until size is 2 again. Track the maximum window size.

4. Analyze complexity

State that the time complexity is O(n) because each element is visited at most twice, and space complexity is O(1) since the frequency map holds at most 3 types temporarily.

5. Test with examples

Walk through a small example (e.g., [1,2,1,3,4]) to verify the algorithm and discuss edge cases like all same type or alternating types.

Key Points to Mention

Sliding window technique with two pointers
Using a hash map to count frequencies of candy types in the current window
Condition to shrink window: when number of distinct types > 2
Time complexity O(n) and space complexity O(1)
Edge cases: empty input, single type, all distinct types
Connection to 'Fruit Into Baskets' problem (LeetCode 904)

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