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Zest

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Zest is a financial technology company that provides AI-powered credit underwriting and machine learning tools to help lenders assess risk and make more accurate lending decisions. It is known for its software that aims to expand access to credit while reducing bias and improving loan performance.

2 interview notes · updated Jul 2026

Zest·Data Scientist·Technical Phone Screen

Jun 2026
Two coding problems for a Data Scientist role at Zest. Nothing too wild but the meeting rooms problem took me longer than I'd like to admit.
  • Find the maximum depth of a binary tree, where depth is the number of nodes along the longest root-to-leaf path.
  • Given a list of meeting time intervals, find the minimum number of conference rooms needed to hold all meetings without overlap. Meetings are half-open intervals so back-to-back meetings don't conflict.

“Went with recursion right away, base case returns 0 for null nodes and you just take the max of left and right subtree depths plus one.”

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Zest·Data Scientist·Technical Phone Screen

Jun 2026
Zest data scientist interview that leaned hard into ML fundamentals. The main question was a classic overfitting diagnosis scenario presented as a plot, and they wanted you to walk through the whole thing: identification, root causes, how to properly validate, and fixes.
  • You're shown a plot where training error keeps dropping but validation and test error plateau then rise, creating a widening gap. What's the most likely issue, what causes it, how do you confirm it without leaking the test set, and what would you actually do to fix it?

“This is a four-part question wrapped in one, which I didn't fully appreciate until I was already halfway through answering just the first part.”

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