The interviewer seemed reluctant to hire someone. He spent 10 minutes on the introduction and selected a tough, complex Python question. While I was coding, he didn't listen. When I asked a clarifying question, he suggested I run the code myself to verify my understanding. He then shut down the coding pad without a word or making up for the time he'd occupied. This was the most unprofessional and impolite interview I have ever experienced.

This is not a typical algorithm question.

It requires recursion, division into different situations, and consideration of many edge cases.

I believe the question's difficulty level is far higher than the requirement for a mid-level data engineer.