I only had the first technical screening round, which was 45 minutes long. The interviewer directly asked a LeetCode hard problem.

The interviewer was not interested in helping or giving hints.

I somehow managed to solve the problem for some test cases the interviewer had, and all passed.

It seems the interviewer didn't solve the problem himself; he just knew the solution and wanted the correct answer. He took an extra 10 minutes where he worked on identifying a test case that failed.

Overall, given the length of the interview (45 minutes), a LeetCode hard problem can only be solved if you have previously solved the same problem and remember each step. Otherwise, devising a solution there without hints is difficult.

Overlapping intervals with weights or priority.