The recruiter set up the phone interview based on my Java experience with TripAdvisor.

It was a Skype telephonic interview where a programming question was presented, and I had to write the program on a shared board.

I was asked to write a program to find common items between two lists. I used Java to write the program.

I wrote the program by iterating through the smaller ArrayList and using the contains() method. The hiring manager argued that the code was not efficient enough, stating that the contains() method on an ArrayList leads to O(n) complexity, resulting in an overall complexity of O(m*n) (which is incorrect).

In the interview, I was not able to Google this and was taken aback when he spoke so assertively, as I assumed he understood Java. However, after I hung up the phone, I realized I was indeed right and that the algorithm I created was very efficient.

The interviewer seemed to have come to the interview with a predetermined view to reject me. It felt like a waste of time. They should let subject matter experts conduct interviews, not people with C/C++ backgrounds interviewing Java candidates, or vice versa. The hiring manager seemed to have a professorial background.

I tried to tell the recruiter to inform them about the problem, but I don't think she has any clue on how to approach it.