Zomato Interview

Round 1 - Technical (60 minutes)

This round began with a discussion about my previous work experiences at startups. The interviewer then delved into some core backend concepts:

• How scaling pooling works
• The differences between processes and threads
• When to opt for multithreading versus multiprocessing

Having a backend background, I felt comfortable answering these questions.

Next, I was given two SQL problems. The first involved writing a query to find employees who earn more than their manager from an employees table (emp_id, name, manager_id, salary). The second, using the same table, required finding the number of employees reporting to each manager, specifically showing only managers with at least 3 direct reports. I solved both using self-joins and a combination of GROUP BY and HAVING clauses.

The DSA segment presented a graph problem. First, I had to find the shortest path distance from a source node to all other nodes. I used BFS for this, achieving an O(V+E) complexity. The second part was more challenging: identify which edge removal would cause the maximum number of nodes to become unreachable from the source. My initial approach involved trying to remove each edge and re-running BFS, and I also discussed optimization strategies with the interviewer, who seemed satisfied.

A few days later, I received a call confirming that I had cleared this round and that my next interview was scheduled.

Round 2 - System Design (75-80 minutes)

This round was conducted by a Senior Engineer. We started with a brief chat about my work experience and some general tech topics for the first 5-10 minutes.

The core of the round was a system design question: Design a food order tracking system. The requirements included real-time updates for users (order confirmed, restaurant preparing, delivery partner picked up, delivery partner location, order delivered), handling concurrent orders, and delivering updates to millions of users in real-time.

Over about 70 minutes, we had an extensive discussion covering:

• The choice between WebSocket vs Server-Sent Events for real-time updates
• Utilizing a message queue like Kafka for order status events
• Designing the database for orders and delivery tracking
• Using Redis for caching active delivery locations
• Strategies for handling connection drops and reconnections
• Crucially, how to scale WebSocket servers for a large user base

There was a significant back and forth on the tradeoffs of different architectural approaches.

Towards the end, for the last 15 minutes, I was given a coding question: Design a basic rate limiter. The task was to implement a function that returns true/false based on whether a user request should be allowed, adhering to a constraint of max N requests per minute per user. I implemented a solution using a sliding window approach with timestamps. The interviewer then probed about memory optimization, leading to a discussion about the token bucket algorithm, which I didn't have time to implement.

I cleared this round as well, receiving confirmation after a few days.

Round 3 - Zomato's Culture Round (30 minutes)

This final round was more focused on culture fit and felt somewhat like a formality, especially after clearing the first two technical rounds. The interviewer was a VP-level individual with extensive experience.

For the initial 10 minutes, he inquired about my background, what I was looking for in my next role, and specifically why I was interested in Zomato. Following that, he provided insights into:

• The team structure and who I would be collaborating with
• The day-to-day work culture at Zomato
• Work-life balance, honestly mentioning crunch times during peak periods
• Growth opportunities and the performance review process
• The current tech stack and ongoing projects

Towards the end, we discussed compensation. He shared details regarding the base salary, ESOP structure with vesting schedule, and standard benefits. I had the opportunity to ask questions about the role and team, making it a very open conversation.

He concluded by mentioning that HR would send the official offer letter in a few days, which I subsequently received via email within 2-3 days.