Platform9 Systems Interview Experience

Round 1(Pre-interview assessment): (3-4 days virtual)

• Selected students (based on our CGPA probably) were sent with problem statements through email. 
• We were given about 3 days to complete and send the assignment using any language of choice. 
• Each student was given a different easy-medium level problem. I was given the problem called ‘Tournament Scheduler’ where input is given as the number of players that will play in the tournament and had to output the schedule of the tournament in a round-robin format.
• Suggestion: I would suggest that students should write a modular solution preferably with proper comments and present their code in an efficient manner understandable to the reader given in this case sufficient time was given for submission of the solution. 
• Based on the submission I was selected for the next round. 

Round 2(Technical Interview 1): (35-40 minutes)

1. Tell me about yourself.
2. The interviewer asked about the final year project. He further asked questions related to the project.
3. Pillars of Object-Oriented Programming.
4. Polymorphism and its types (Compile-time and Runtime).
5. Virtual functions.
6. Inheritance.
7. Difference between Process and Threads.
8. Parallelism and Concurrency.
9. Semaphore, Mutex.
10. Deadlock and its necessary conditions.
11. Deadlock handling methods and prevention.

Tips: 

• Explain concepts if possible with real-life examples. 

Round 3(Technical Interview 2): (45-50 minutes)

1. The interviewer asked me to introduce myself.
2. Discussion on projects mentioned in the resume.
3. I have used firebase as a database in one of my android based projects. From there we went to discussions over SQL vs NoSQL and further related questions.
4. Define Threads.
5. Mutex, Semaphore.
6. There was a rapid-fire DBMS round in which he asked the following questions :
          Primary key, foreign key
          Normalization and its types
          Difference between TRUNCATE (DDL, fast, can’t rollback) and DELETE(DML, can rollback)
          Joins and their types
          Views
          ACID properties
          Indexing and types of indexes
          Data structure used in indexing (B/B+ Trees).
7. He asked to share the screen and gave one input table and asked to write 4-5 queries based on that. They were based on using LIKE, HAVING, GROUP BY, ORDER BY, etc.
8. The discussion then shifted to some basic Data Structures and Algorithm questions. What is BST, etc?
9. He then asked me to write code for the following medium level problem :
   Given a sorted array, remove the duplicates in-place such that duplicates appeared at most twice and return the new length.
10. Initially, I explained my approach and proceeded to write the solution. I first used extra space to solve the problem. He then asked to optimize it by using O(1) extra memory. He gave some hints and I was to some extent satisfy him. Solved it using two pointers approach.

Tips:- 

• You should be thorough with your Resume. 
• Tell the time and space complexities of the solution.
•  Talk out loud about your thought process and clear every doubt related to the question.  
• Look for hints by the interviewer if stuck on the problem. 

Round 4(Technical Interview 3): (30-35 minutes)

1. Tell me something about yourself.
2. He asked about Operating Systems. Started with the definition of Process and Threads. Differences, etc.
3. The interviewer explained to me the Producer-Consumer problem and asked me to write pseudo code for the same.
4. I used basic enqueue and dequeue operations, threads, and locking concepts to avoid race conditions.
5. Then he asked to write the enqueue and dequeue operations for queue using linked list.
6. He then questioned me that do you have any idea about Microservices, Docker, Distributed Systems, live debugger, linux, etc. He explained few terms I was not aware of.
7. The interviewer asked me whether I had any questions.

5 students were selected and I was one of them!

Stay confident and calm. All the best!