In the first interview, i was asked to solve few coding challenges in optimal approach in terms of time and space. It consisted of a question which expects some twists using arrays and the other question expects to use a tree. I answered them both and got selected to second round of interview. In the second round, the interviewer gave me a coding problem and asked to solve it. I have answered it using heaps. She told me she's expecting more optimal approach. In the end, i asked her what could the better approach than using heaps and she answered saying to use 'Priority Queue'. I was pretty much shocked to understand that the interviewer doesn't know that both are same. 'Priority Queues are nothing but using heaps. There's nothing else' I explained her saying that priority queue is just one fancy name for what i already implemented using. She asked me another question to which i answered using graphs and she's convinced here. Also i found her going away from the interview session and rejoining after sometime after my second question. The interview is done and i didn't get the position. PS: i gave optimal solutions to both the problems asked and i wasn't asked any other questions. The only thing here is the lack of knowledge of the interviewer!