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TikTok·Machine Learning Engineer·Online Assessment (OA)·Intermediate

Intermediate
Jun 2026

Summary

TikTok ML engineer interview with a coding problem focused on finding the largest numbers. Not much else to go on from what I remember.

Questions Asked (1)

Q1

Given a dataset or array, find the largest numbers according to some criteria.

Algorithms & Data Structures
Author's notes

Pretty bare bones problem on the surface.

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AI HintsAI Generated

Suggested Approach

Start by clarifying the problem: what 'largest' means (e.g., top-k, max, threshold), the criteria (e.g., by value, by multiple attributes), and constraints (data size, memory, streaming). Then propose an efficient algorithm, such as a heap for top-k or sorting for full ordering, and discuss trade-offs. Finally, consider edge cases and potential optimizations for large-scale data.

Pro tip: Demonstrate awareness of real-world ML data pipelines by mentioning how you'd handle streaming data or distributed processing (e.g., using MapReduce or Spark) when the dataset doesn't fit in memory.

1. Clarify requirements

Ask questions to understand the exact problem: what defines 'largest' (value, score, multiple criteria), how many largest numbers are needed (top-k or all), and the data characteristics (size, type, distribution).

2. Choose algorithm

Select an appropriate algorithm based on requirements: for top-k, use a min-heap of size k (O(n log k)); for finding the maximum, a simple linear scan; for sorting all, use comparison sort. Discuss time and space complexity.

3. Handle edge cases

Consider edge cases such as empty array, k larger than array size, duplicate values, negative numbers, and data with multiple criteria (e.g., sort by one key then another).

4. Optimize for scale

If data is large or streaming, discuss approaches like maintaining a heap for streaming top-k, or using distributed computing (e.g., MapReduce) to find local top-k then merge.

5. Test and validate

Walk through a small example to verify correctness, and mention testing with random data and comparing against a brute-force solution.

Key Points to Mention

  • Time and space complexity of different approaches (e.g., sorting O(n log n) vs heap O(n log k))
  • Use of a min-heap for top-k problems to maintain the k largest elements efficiently
  • Handling multiple criteria: e.g., sort by one attribute, then another, or use a custom comparator
  • Streaming or distributed processing for large datasets (e.g., using a heap for streaming, or MapReduce for batch)
  • Edge cases: empty input, k > n, duplicates, and stability of sorting
  • Python-specific implementations: heapq.nlargest, sorted with key, or numpy.argpartition for efficiency

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