There were three rounds of interviews. all of them were about testing technical skills .all of the questions were about data structures . they were pretty standard. i was able to clear till second

I got call from a recruiter who scheduled a telephonic interview. Questions related to current and previous work experience, technologies/tools used and algorithms were asked. The interviewer asked following questions: 1. Internals of HashMap, equals() and hashCode(). 2. How HashMap handles key collisions. 3. Maximum capacity of HashMap can have. 4. ConcurrantHashMap internals. 5. Top view of binary tree. Answer to the 2nd question led to a point where the interviewer suggested me to read more on HashMap (According to him even if we put total number of distinct entries > Integer.MAX_VALUE hashMap's performance will not degrade and it still can perform add and delete operations in O(1) time). I shown him my disagreement with the above explained theory of him, but he continued insisting me that I have a wrong idea about working for HashMap. I didn't expect to clear this round because of above discussion. But, a week after I got invite for F2F round. Before the F2F interview started there was an HR interview which lasted 10 mins. After that technical F2F interview started. The interviewers started with asking about my brief introduction. He started with Mongodb related questions as he was also using Mongodb in his projects. He seemed more interested in displaying his approaches. 1. What all features of Mongodb I have worked with. I replied Full Text search, Geospatial index and Aggregation pipeline among the important and other things like indexes, compound indexes etc. 2. He asked a followup question: what is Full Text Search and why do you need this I explained him how FTS works and explained my use case. After which I started showing how faster regex queries run on Mongodb, and because of this I should not have used FTS. He was displaying time taken by his regex queries on Mongodb. When I suggested that FTS is a different kind of beast and should not be compared with regex queries on Mongodb and FTS will outperform regex queries, He still was showing his disagreement and continued showing his query time for next 10 minutes. 3. What are compound indexes on mongodb and how do they work. 4. Internals of ArrayList, HashSet and fail fast iterators. 5. CopyOnWriteArrayList internals and fail safe iterator in this case. 6. Caching strategy in the projects I have worked on. 7. Given a NxM matrix of integer find a path for which sum of all the cell values on the path is maximum. (DP) 8. Write code for 2 player game in which starts with a initial list of integers. Each player can pick one of the two integers on beginning or end. Each selection should lead to a total sum which is maximum for player 1. Couldn't answer this question. After this round I waited for 10 minutes on reception and was informed by the security guard that I can leave for the day because I didn't cleared the round.