Telephonic Conversation with HR (5-10 mins)
HR asked a few questions about the current organization – CTC drew, tech stack, reason for the switch, etc.
HR explained the interview process – 3 Technical Rounds
- Technical Round 1 – DSA
- Technical Round 2 – Coding
- Technical Round 3 – LLD
Technical Round-1 (DSA): (1 hr)
The interviewer was an SDE-2 with 3-4 YOE.
- We started discussing about my previous project for around 10 minutes.
- Then, jumped straight to problem-solving.
Problem 1 (LC- Medium): https://www.geeksforgeeks.org/nth-node-from-the-end-of-a-linked-list/amp/
- Explained 2 approaches to the problem.
- Coded the optimized solution in personal IDE.
- Then did a DRY run with the sample input and showed the output.
- He was satisfied with the solution.
Problem 2 (LC- Medium): https://leetcode.com/problems/longest-substring-without-repeating-characters/description/
- Explained to him the naive approach first and then was asked to optimize it.
- Gave the optimized solution using hash maps and sliding windows.
- Did a dry run first, then he asked to run sample test cases and all passed.
Then, he asked to write an SQL query to fetch 2nd highest salary of the employee from the employee table.
So, by then we were almost done with the interview. He asked for any questions and concluded the interview.
Feedback: Positive, As I was able to solve all the problems. Got the call the next day from HR that I was shortlisted for round 2.
I asked HR about the topic of discussion for the next round, she said it could be anything around DSA, CS Fundamentals System design etc. So, I was not sure about the discussion for the next round.
Technical Round 2 (Coding): (1 hr)
When I joined the call, HR informed me that the Interviewer would be a bit late for conducting the interview and she asked me to wait for 10-15 mins. After 15 minutes, he joined the call and apologised for being stuck with the previous meeting.
We started with him giving his introduction. He was an engineering manager with 12 YOE and then he asked for my intro. He asked me about the topic which I would like to discuss on. I said JAVA. Then he started with it.
JAVA and OOPS:
- What are the four pillars of OOP? – I explained each in detail each pillar with examples on my IDE.
- There was a depth discussion on every pillar with real-life examples. The recruiter was asking counter questions on my examples.
- Why String is Immutable in JAVA? – I did not know about it, so I said that I knew how to resolve immutability by using StringBuilder and StringBuffer classes. But don’t know exactly why it was made immutable. The interviewer was kind enough to tell me why it was immutable.
Design Pattern and Multithreading:
- He asked if I knew the singleton design pattern and asked to implement it.
- Then he asked about some concepts related to multithreading and how to ensure that singleton class is thread-safe.
- I explained about thread synchronization and then he asked about the importance of double null checks in singleton design patterns.
- We jumped on the system design problem.
System design and DB Schema:
- He asked me to design DB Schema for every actor- Customer, Restaurant owner, and Delivery Partner in a food delivery app like Swiggy/zomato by giving relevant details of the fields chosen.
- We had a discussion on it and areas where the design could be improved.
By then, we were almost finished time for the interview – So, so he concluded by asking if I had questions for him.
This was the best interviewer I had got to date. He was a chill dude and had interviewed as if two friends were talking to each other. Didn’t get a vibe of manager at all.
Feedback: Positive, Received the call the next day from HR that I made it for the final round.
Technical Round 3(LLD): (1 hr)
The interviewer was again a manager with around 10 YOE.
We started with his introduction first and then with mine. He was someone who worked in my previous organization so, had a 2-3 min chit chat on the company.
Project discussion (10 mins) :
- He asked me to explain any of the projects mentioned on my resume.
- I did that for around 10-15 mins. After that, we jumped on the LLD question
System design :
- He asked me to design a payment app similar to Google Pay with the functionality of QR code payment, Bank transfer, Pay to contact and pay history.
- He said that I could use any online whiteboard portal to draw the components.
- I started with the requirements first and then moved to draw.io for the components.
- We had a long discussion on designing components and after that, he jumped on to the DB
- He asked me to create whatever DB would be required for it.
- At last, he asked SQL queries related to my DB design. By then, we were done with the interview.
Feedback: Mixed, The interviewer was expecting some of the components to be discussed in more detail- like in pay history, what mechanism you’ll follow to store information in DB, API callback and time out etc. I was a bit confused answering them.
I got the call from HR the next day that I had made it through all the rounds and had been selected.
Verdict: Selected