Years of Experience: ~5 years
Location: Bengaluru
I recently participated in an SDE-2 interview with Dream11 and would like to share my experience. I was contacted by a recruiter on LinkedIn, and one week later, the first coding round was scheduled.
Round 1: Coding Round
Format: Virtual – 29th March, 2024
Task: Write the solution in a text editor and dry run the test cases while explaining the logic, space, and time complexity.
Problems solved:
- Minimum Path Sum
Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right, which minimizes the sum of all numbers along its path.
Note: You can only move either down or right at any point in time.
- First Missing Positive
Given an unsorted integer array nums. Return the smallest positive integer that is not present in nums.
You must implement an algorithm that runs in O(n) time and uses O(1) auxiliary space.
Result: Positive
Round 2: DB and Project Round
Format: Virtual Round – 8th April, 2024
1.) I was asked to explain the internal architecture of one of my projects.
2.) I used an online drawing tool to explain the DB schema and architecture, and questions were based on that.
3.) They asked why CDN, why LB, basically questions on overall architecture components and why of it.
4.) Also since my system used MySQL, many questions were focused on MySQL topics such as:
Isolation levels
Pessimistic vs. Optimistic locking
Indexing
Unique key indexing
Result: Positive
Round 3: HLD [On-Site Mumbai] – 27th April, 2024
Travel: Flight tickets were arranged.
Initially, they inquired about the technologies I have worked on to decide the system design question.
Questions included:
Internal implementation of Redis lists
CDC with Debezium
Which isolation level is used in your databases
After about 10 minutes, they asked me to design a system for sending lineup notifications to Dream11 users, which are sent 30 minutes before the start of a match.
The system needed to be elastic, capable of handling scenarios where only 1000 users have joined a contest or even millions.
Input was from two Kafka streams: one for users joining the contest and the other for the contest lineup info.
Proposed Solution: Redis + Spark
Other interviewees were asked to design systems like the Dream11 leaderboard and Dream11 digital wallet.
Result: Positive
Round 4: HM Round
Questions included:
- How would you hire people if you were an interviewer? What qualities would you look for?
- What is your feedback on your previous rounds?
- Discussions on how we have implemented functionalities in our payment systems.
- What data do you use to monitor your services?
- What does the availability of a system mean, and how do you define it?
- What metrics do you track to ensure your services are running fine?
- Describe a scenario where you failed in some projects or were disappointed by your manager’s decisions.
- What would your manager say about you if we asked why we should hire you?
- What would your manager say about you if we asked why we should not hire you or things you can improve on?
Overall Result from all rounds: Not selected.
The HR highlighted positive aspects, but noted that there were some technical areas where I lacked.
From my point of view, I used some hints given by the interviewer related to spark as I did not used it just knew from high level like how internally you will schedule the jobs what parameters you will pass etc.
Tip:
When you attend an on-site interview, they usually have two people interviewing you, and nowadays all rounds happen virtually, so make sure you are well-prepared for that environment. I got nervous in between since one interviewer might ask one thing and the other something else. You need to maintain coordination.
Also, know the in and outs of your past projects and tech stack, why you used them, etc.
For the HLD round, I suggest reading many case studies but also try to think about the “why” of everything. In an interview, they can ask you anything, and understanding the basic system design blocks of distributed architecture will help.