Resumable List/File Iterator

Also reported as Resumable Iterator · 2D Resumable Iterator · Resumable Multi-File Iterator

CodingOpenAILast reported June 2026Medium Frequency
Reported
5× across candidate reports
First seen
January 2025
Last reported
June 2026
Reported outcome
mixed

Problem Overview

OpenAI coding question, reconstructed from 5 candidate reports (January 2025 to June 2026). Tests: iterators and generators; serialization and encoding. Candidates reported 6 follow-ups. The write-up includes a Python solution that passes 11 test cases.

  • 6 candidate-reported follow-ups — the probes candidates report being asked, with the trigger for each
  • The full problem statement — full requirements, constraints, and edge cases
  • Approach and trade-offs — what passing candidates did, and the mistakes that sink people
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Verified Source
Every question is reconstructed from multiple independent candidate reports. Follow-ups candidates reported, not invented ones.
Codex Fact-Checked
Technical claims, formulas, and scale numbers are reviewed against primary sources.
Interviewer Follow-ups
The follow-ups candidates reported, with the trigger that prompts each one — plus the mistakes that sink people.
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