SquadStack Interview Experience for Product Engineer

I applied through On-Campus Placement Drive. They took 6 rounds in total. Due to covid, all the rounds took place online.

Round 1(Aptitude Test):  There were 100 MCQs based on Aptitude and Logical Reasoning without Negative Marking.

Round 2(Coding Test 1): After clearing the first round they will send you a link for coding questions. 

• There were 4 questions and choices in 2 of them so we have to attempt 3 questions and 1 of them was based on Inversion Count, 2 were on implementation, 1 was on graphs.

Round 3(Coding Test 2): After clearing round 2, they will send you a link for another coding round. 

• There were 10 MCQs based on PostgreSQL, DBMS, Computer Networks, and 2 Graph Questions (Medium to Hard Level).

Round 4(1st Interview -> Tech Deep Dive + Coding Round): It lasted for around 1 and half hours. 

• Some basic questions were asked from CS subjects like the difference between SQL and NoSQL, normalization and denormalization, Authentication and Authorization, CAP theorem, Race condition, Deadlock, NULL/Dangling Pointers, Call by value/reference, abstract classes, API Calling, Typecasting, Compile-time polymorphism, Runtime polymorphism, Static and Dynamic programming languages, some general questions like which databases you have worked upon and was that related to SQL or NoSQL, etc.

Then there were 2 coding questions asked:-

• First was similar to these -> https://www.geeksforgeeks.org/find-duplicates-in-on-time-and-constant-extra-space or https://www.geeksforgeeks.org/problems/find-duplicates-in-an-array/1
• The second was similar to this -> https://leetcode.com/problems/basic-calculator-ii/

Round 5(2nd Interview -> Bar Raiser/Design Round): This was a System Design Round and lasted for 1 and half hours. 

• They first asked me about basic features of Instagram, and then asked me to design the schemas which were needed in this. So you have to think of necessary tables options like User Login, Posts, etc and before every step, you should ask him whether you should consider this or just ignore this because in this round you have to make conversation with the interviewer and let him know whatever you are thinking. 
• There I created 5 different tables and then one by one he asked me about the fields inside them and which one to make primary key, foreign key, their data types, why is it necessary, etc. Also after making fields, he asked me to design API requests like using an API, how can I fetch my own posts, my followers list, etc., and their SQL queries were also asked. 
• My suggestion for readers is to practice DBMS concepts and SQL queries for this round like ORDER BY, WHERE, TOP, subqueries, etc.
• After this, he asked me which servers I will need to design this and then he asked me like you have a database having millions of records and queries are coming at a rate of 1000 queries per second then how will you make it fast, for this I recommend readers to study about Load Balancers, and then he asked some questions related to this only.

Round 6(3rd Interview -> Culture Fit Round): This round lasted for around 30-35 mins and in this, I was asked some behavioral questions like why you want to join us, why you selected engineering if you are given 3 offers from different big companies then which one would you choose, and why.

• Then he asked me the same ques but now offers were from Startups.
• Then he asked me what was the most challenging problem you faced till now and how you tackled it, which interview round you think was the best and in the last, he asked me whether I want to ask some questions or just end the interview so I also asked 1-2 questions and then interview ended.

I would recommend the readers to prepare their CS Subjects specially DBMS.