SDE-1 at Blinkit

How it went

What they would tell you

How to prepare

Round by round

1. 1

   Problem Solving + DSA60 min

   The first round was more of a technical discussion rather than just a coding test. The interviewer started with a general introduction, where he asked me to talk about my internship experience and some projects I had worked on. This was followed by some interesting DSA and SQL questions.

   • Group Anagrams Problem (Coding) - I solved this by using a hash map to group the anagrams efficiently.
   • SQL Join Types: He asked me about the difference between INNER JOIN and LEFT JOIN, and when to use GROUP BY and HAVING clauses.
   • Inactive Users Query: Given a user table with a last login date column, I was asked to write an SQL query to find users who hadn’t logged in for more than 90 days.
   • We discussed my project’s HLD (High-Level Design). I had to explain my design decisions around using RabbitMQ vs Kafka, the purpose of using cache, and why I chose PostgreSQL for the project.
   • He gave me a scenario where the app started receiving a lot of users. I was asked to explain how I would modify my design to handle a higher load.
   • This round lasted around 1 hour, and I felt confident at the end. A day later, the recruiter called and confirmed I passed, and we scheduled the System Design round.
   • Group Anagrams
2. 2

   Technical Round60 min

   In the System Design round, I was asked to design a discount-coupon creation system. This was a design-focused round where I had to demonstrate my ability to create a system that handles multiple functional requirements. Functional Requirements:

   • Coupons can be created based on rules provided by the admin.

   • Coupons have an expiry date and a limited number of users who can use them.

   • The user has a 5-minute window to apply the coupon code during checkout. Design Discussion:

   • I started by outlining the API endpoints, database schema, and the overall logic.

   • The interviewer then asked me to think about scalability, especially if the system started having millions of users. I mentioned strategies like caching, load balancing, and partitioning. The interviewer was pleased with my approach and the design decisions I made, and he suggested improvements to the storage layer.

3. 3

   HM and Culture Fit Round60 min

   This was a more conversational round with the Hiring Manager (HM). The HM was very relaxed, and the interview started with introductions and small talk. Then, we moved on to the technical discussion:

   • The HM asked me about my project experience and how I handled certain situations like managing large-scale systems. Database Questions:

   • We discussed Kafka vs. Databases. The interviewer was keen on understanding my thought process when choosing between a NoSQL database and event streaming systems for handling high throughput. Behavioral Questions:

   • “How do you handle high-pressure situations when things go wrong?”

   • “What did you learn from your previous projects, especially around teamwork and leadership?”

   • I was also asked how I work in teams and my ability to collaborate in cross-functional teams. Finally, the interviewer asked me about my career goals and why I was interested in Blinkit. He mentioned how the Data Platform Team at Blinkit works, and I was able to ask a few questions about the team dynamics. This round lasted 40 minutes, and the HM seemed satisfied with my answers.

What came up