Round 1: dsa

Asked to code in JAVA only(though i have work experience in Java, I prefer cpp stl for coding)
Asked to code in notepad...
=> find sum of elements in tree, by adding sum=leftsum+rightsum+currsum;
=> insert linkedlist2 at nth position linkedlist1 (Handle all edge cases)

Round 2: lld
Design your own library which can invoke rest calls to external systems

functional requirement:

1. provide clients to invoke post and get calls
2. ability to select choice of implementation during the invocation-> Spring rest template/apache gttp client/ ok http client etc..

non-functional requirement:

1. design should adher to OOPs and Solid
2. ease of adding new choice of implementation
3. code should be unit testable

questions faced on my design:
which pattern you should use

why factory? why not strategy, can composite pattern be used.

when do we use factory and when strategy

There is a interface which has 3 abstract methods. now already there is a production running code which has 2 concrete implementations implementing this interface. Now i have a new implementation which have to just implement 2 abstract methods in the interface, how to handle this

Round 3: HM round

where do you look yourselves in next 5 years
what do you do when friend doesnt co-operate

explain complete architecture of your feature in your work
Unit test cases for it

how do you scale from 100 to 1M request
why sql for your feature

how to ratelimit
how to would you design error messages automatic alerts
how would you check bugs

how do you maintain code reviews

Round 4
HR round: basic HR questions

My Current Comp for 2.5 YOE:
25.5 CTC: 20.5 Base, 2 Varibale, 3 Joining Bonus

Walmart is my first offer with
25 Base, 5 annual bonus, 6L Rsus(3Years)