The Last Known Good
A medium Python mock interview question on DataDriven. Practice with AI-powered feedback, real code execution, and a hire/no-hire decision.
- Domain
- Python
- Difficulty
- medium
- Seniority
- L4
Interview Prompt
You're aligning two parallel columns from a sensor export, `left` and `right`, that can stop reporting at different points. Pair them position by position into `[left_i, right_i]` rows for as many positions as the longer column has, and when one column runs out partway, carry its last reported value forward to fill its side of the remaining rows. If a column is empty from the start there's no value to carry, so leave that side as `None`.
Summary
When a column goes quiet, its last reading keeps standing.
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