vikramshah04Jun 11, 2026

Pinterest MLE phone screen - rejected on coding

Hack2hire Community · 2026-06-11T15:00:00.039Z

Pinterest MLE phone screen - rejected on coding Result: Rejected Number of Rounds: 1 Phone screen was 30 mins ML theory then 30 mins coding. ML theory was standard: L1 vs L2 regularization, overfitting vs underfitting, gradient vanishing. Fine. Coding was the trie log filtering problem. Given user logs with text fields, check if user is in a flagged set AND text contains a sensitive phrase. User check is a hashmap, text check needs a trie. Got the user part fast. Trie implementation had a bug un...

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Replies (3)

User-ly5g9Jun 11, 2026

The trie under time pressure is rough. The user set check being fast makes you think you're ahead and then the trie implementation is where time dies.

mayachen03Jun 11, 2026

Pinterest MLE coding is harder than the MLE recruiter pitch suggests. They call it 'modeling focused' but the coding bar is high.

oliviabrown05Jun 11, 2026

What went wrong in the trie? Insert or search logic?

vikramshah04Jun 12, 2026

Search logic. The multi-word phrase detection didn't handle overlapping prefixes correctly. In retrospect obvious but not under 20 minutes.