Knowlarity Interview Experience | Set 2 (Off-Campus)

I applied for a job through there official website(I saw the job opening and mailed my resume to the HR). He immediately responded and sent me a link for an online test.
It had 2 coding problems. Later, the next day he called up and asked three aptitude questions. I was later on called for a f2f interview.

Round 2 : I was asked to code. A computer was provided.
Question : A calculator application that takes 2 numbers as input and an operation to perform.
Condition : The number’s digit count will be greater than 50.
Solution : I scanned it as a string and performed the operations digit-by-digit from right to left.(Did not perform division, it was time. I took 1hour for addition,subtraction and multiplication. Reused addition logic for multiplication)

I cleared that round and went on to next round.
Round 3 : It was a f2f interview over hangout. I was asked various algorithm and Data structures based questions.
Problems like finding loop in a linked list, which is the best sorting technique? why? , He asked me to code a small program to perform addition of two integers by call by reference.
I used Integer object in java.
I passed that round.

Round 4 : I was asked to rate myself on programming,algorithms,Android SDK(since i am a android developer) and DBMS. Then he started interviewing me about the algorithms and slightly about android.
Puzzle : 100 floors and an egg puzzle. After deducing, i came up with binary search algorithm(i did not know the solution). He said why not tertiary search? He wasn’t convinced with my answer.
Since they work on NodeJS, he gave an assignment on NodeJS. I had to use NodeJS, Redis and MySQL for basing insert/delete and update operations. I left foe the day.
2 days later i sent my assignment. A week later they called back for further interviews.

Round 5 : The same person form round 4 came and asked the same question ‘why not tertiary search? ‘ . I said the same old answer. He went out – HR came and told me that the manager wasn’t convinced. They were polite and nice.
I failed that round. But the interview quality was too good.
Mistake : After an interview, always research the questions that were wrongly answered.