Walmart SSE iterview experience
Summary
I interviewed for a Senior Software Engineer (SSE) position at Walmart in Bangalore, which included DSA, HLD, and LLD rounds. Although I cleared the initial rounds, I was rejected after the LLD round where the interviewer was not satisfied with my design and approach to scaling.
Full Experience
July 3rd Onsite Hiring Drive for Bangalore:
YOE: 6years
Round 1: DSA 60min(Onsite round: cleared) 2 Leetcode medium questions
Solved both with optimal approach.
Round 2: HLD 60min(Onsite round: cleared) A) Discussed on how to handle concurrent access of threads in DB for a transaction.
B) Design Twitter:
Design a simplified version of Twitter with the following core features:
- Users can post tweets.
- Users can view a feed that shows tweets from the people they follow, ordered by most recent first.
Discussion Highlights:
- The interviewer focused heavily on database design and schema structure.
- We discussed how to make the system scalable, especially with a large user base.
- There was significant emphasis on how to optimize for fast reads, and the trade-offs involved between read and write operations.
- Caching strategies and feed generation approaches were discussed.
Next day: Round 3: Java + LLD 60min(Virtual round: rejected)
The round was supposed to be 30min Java + 30 min LLD.
But we did not discuss anything about Java domain. I taked about one project on a very high level, while I was excited to talk in depth but interviewer immediatly moved to LLD.
LLD: Design a Notification System that can send notifications via email, SMS and WhatsApp.
I designed it using Observer+Strategy pattern. But interviewer was not satisfied, asked me to think of something else to scale the design for 1000s of services.
I attempted to Scale the design, but struggled to discuss the approach.
There were total 4 techical rounds - DSA, Java+LLD, HLD, HM. Each round was elimination round.
The interview process was smooth and feedback was given instantly by the Talent Coordinator.
In the third round, the interviewer felt I was reading from somewhere else, I lost my train of thought right after hearing this during the interview and clarified that I wasn't (my entire screen was shared the whole time, and I was facing only the screen). After this bad experience, I felt the onsite interviews are far better than virtual (ignoring the inconvenience caused by traffic). Atleast the interviewer constantly would not doubt the candidate.
Interview Questions (5)
Discussed on how to handle concurrent access of threads in DB for a transaction.
Design a simplified version of Twitter with the following core features:
- Users can post tweets.
- Users can view a feed that shows tweets from the people they follow, ordered by most recent first.
Discussion Highlights:
- The interviewer focused heavily on database design and schema structure.
- We discussed how to make the system scalable, especially with a large user base.
- There was significant emphasis on how to optimize for fast reads, and the trade-offs involved between read and write operations.
- Caching strategies and feed generation approaches were discussed.
Design a Notification System that can send notifications via email, SMS and WhatsApp.