Machine Learning Engineer · Onsite · Multiple Types

Google — Machine Learning Engineer ❌ Failed

Level: Senior-Level

Round: Onsite · Type: Multiple Types · Difficulty: 7/10 · Duration: 120 min · Interviewer: Unfriendly

Topics: Natural Language Processing, Behavioral Questions, Coding, Machine Learning System Design, Recommendation Systems, Tokenization, LLMs

Location: San Francisco Bay Area

Interview date: 2026-01-15

Got offer: False

Summary

Round 1: ML Domain and Behavioral (BQ)

Question: Questions about my resume, NLP fundamentals such as comparing tokenization methods, and a mini-case on using LLMs for recommendation.

Round 2: Coding and ML System Design (MLSD)

Question: Coding question on subarray sums, and MLSD question on building a chatbot using structured and unstructured data.

Details

I recently interviewed for an L5 Machine Learning Engineer role at Google. I had been speaking with the recruiter and told her I was already in team match with another company, so she expedited my onsite interview.

The onsite was divided into two rounds. I had to pass the first round to proceed to the second. Because it was a direct team hire, there was only one coding round.

In the first round, I chose NLP as my ML domain. The questions started with my resume, then moved to NLP fundamentals, such as comparing different tokenization methods. Finally, I was given a mini-case: how to use LLMs for recommendation.

I found the Google behavioral questions to be simpler than those at Meta/Amazon, but I don't remember the specific questions.

The coding question was to find the sum of all good subarrays that have a difference of 1 or -1. An example is [3, 5, 6, 7, 6] -> sum([3], [5], [6], [7], [6], [5, 6], [6, 7], [5, 6, 7], [7, 6]). The time complexity requirement was O(N). I got stuck on the spot. A male interviewer gave me many hints, but I still couldn't produce the optimal solution.

The MLSD question asked how to build a chatbot based on structured and unstructured data. I had been asked a similar question at another company, so I answered this round smoothly.

I felt it was a pity that I was rejected, because the recruiter said the other rounds were positive, but I failed the coding round. I guess I need to practice more coding problems. I'll try again after the one-year cooldown period.