HR contacted me and scheduled a phone screen.

The interviewer asked me a coding question, which I solved in about 20 minutes. He then tried to make the problem more complicated, and I solved that too.

For both problems, I executed the code, showed the results, and wrote a few test cases.

I felt the conversation with the interviewer was uncomfortable, as I am much older than him (late thirties).

A few days later, HR sent a rejection with no feedback.

I hope they had a valid and unbiased reason for the rejection.

Standard algo