Machine Learning Engineer · Phone Screen · Coding

Pinterest — Machine Learning Engineer ❌ Failed

Level: Mid-Level

Round: Phone Screen · Type: Coding · Difficulty: 7/10 · Duration: 60 min · Interviewer: Neutral

Topics: Machine Learning, Data Structures, Algorithms

Location: San Francisco Bay Area

Interview date: 2025-12-15

Got offer: False

Summary

I started with self-introduction and a description of a research project.

Then, I answered questions on machine learning fundamentals.

Finally, I had a coding question involving text filtering.

Details

The coding question was:

Given pin logs containing user and text fields, and given a userset and textset, trigger an alert if a user is in the userset and the text contains a sensitive phrase from the textset.

My approach:

• User check: Use a hashmap or set for efficient lookup.
• Text check: Use a trie data structure to detect sensitive words in the text.

I was not proficient in implementing the trie and failed to produce bug-free code within the given time, which led to a rejection.