current company: tier-1
yeo: 5
ctc- 40LPA

Experience:

was contacted by recruiter over LinkedIn.

Recruiter mentioned that I'm not eligible for MTS-4 with my year of experience so went with MTS-3 interview.
I was told there would be 4 rounds depending upon my performance interviews can be reduced to 3 rounds. I had to give only 3 rounds which recruiter mentioned to me after first 2 rounds.

1st round: Coding

Variation of 4 Sum problem. Asked me to code the optimise solution. It took around 40 mins with the discussion and the approach. After that interviewer asked me about my current project and explain it to him in detail. He grilled me little bit on my project.
I felt that the round could have been better if i had coded and discussed the approach faster.

2nd round: Design

This was not like typical system design round.
the interviewer gave me very breif info of the question. He asked me to design Multi tier cache. Given RAM contains 100MB, SSD contains 2TB and then HDD.
With each tier the GET time increases.
I gathered the information as much as i can, We finalised on LRU as the eviction policy. We discussed the solution how we can use message queue to formulate data in each tier.
This round went very well, the interviewer was also satisfied and appreciated me for the given solution.

After this the recruiter told me that I am being moved to team matching Hiring manager round.

3rd round: Director round- Project and code

This round was tougher than other 2 rounds. Interviewer asked me to explain one of my project. He asked everything in detail and about my responsibility and contribution in the project.
In last 10 mins he asked me to come up with the Low level design code for Multi tier Cache. Also he asked me to code in C++, I haven't coded in C++ for last 3 years so was very rusty with the code. I told him the same but he told me to try it out. Still tried as much as I can to write classes and interfaces for the same. But due to lack of time couldn't finish it.
The first 45mins of this round went pretty well.

He told me he understands what I am inferring to in the code.
He looked satisfied and told me the recruiter will reach out to me soon.

Next day I got the rejection mail. Not sure where it went wrong except for 2-3 places where I made minor mistakes or took interviewer's help.

Hope it helps!