The Repeat Visitor
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
Given a list of purchase records (dicts with 'user' and 'date' in 'YYYY-MM-DD' format) and integer days, return users who made at least two purchases within a rolling window: there exist two of their purchase dates d1 <= d2 with (d2 - d1) days <= days. Return the list of user IDs sorted alphabetically.
Summary
Loyal customers come back sooner than expected.
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