The Forward Fill
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
- L3
Interview Prompt
Given a list that may contain None values, return a list of the same length where each None is replaced by the most recent prior non-None value. If a None appears before any non-None value has been seen, leave it as None.
Summary
Patch the gaps in a noisy sensor stream.
How This Interview Works
- Read the vague prompt (just like a real interview)
- Ask clarifying questions to the AI interviewer
- Write your python solution with real code execution
- Get instant feedback and a hire/no-hire decision