I received a call from HR for an onsite interview after applying through an employee referral.

The interviews were a good level, mostly concentrated on problem-solving.

For the second interview, the interviewer didn't know the solution. I explained my solution to him, and he was checking it with an example. At last, when he couldn't disprove my solution, he just let it go and rejected me, stating that I didn't provide the solution he was expecting.

Event scheduling with various modifications.