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The Gap Filler

A easy Python mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.

Domain
Python
Difficulty
easy
Seniority
mid

Interview Prompt

Our time-series pipeline has gaps where sensors report None. Write a function called forward_fill that takes a list with None values and carries the most recent non-None value forward. If None appears before any real value, it stays None - the downstream model needs to know there's no history.

How This Interview Works

  1. Read the vague prompt (just like a real interview)
  2. Ask clarifying questions to the AI interviewer
  3. Write your python solution with real code execution
  4. Get instant feedback and a hire/no-hire decision