PhonePe Interview Experience

I recently interviewed with PhonePe for their SDE II role. Here's how it went.

First Round – Machine Coding Round This round was scheduled by the recruiter via zoom, where I was provided a link to a coding pad with the question. I had to submit the solution via email within 1.5 hours. I was allowed to solve this offline on my editor. It was a typical object-oriented design question. Though I don’t have the exact question now, many similar problems are shared on GitHub by past candidates. I was expected to implement 6–7 functions. You are not expected to complete everything so do it sequentially. I managed to complete all 7 functions, even though there were mistakes in the last one.

The focus was clearly on implementing a working solution in a short timeframe while ensuring modularity, scalability, and OOPs.

The very next day, the recruiter reached out to schedule a follow-up with engineers to discuss the code.

Second Round – Code Review & Deep Dive This was essentially a code walkthrough with two engineers from the team. Using the example they'd provided, I explained the flow and logic across each function.

They asked questions around concurrency and thread safety. My code was not thread safe and I told them in the interest of velocity I have written this, but ya i would introduce locks otherwise. They also asked some questions around different scenarios and how I would implement that.

It felt more like a peer review than a grilling interview, and overall, the round went smoothly.

Third Round – DSA and Problem Solving I was asked two LeetCode-style questions:

Matchsticks to Square: I initially misread the example due to confusion around the input format, which cost me a bit of time. But once I understood the problem, I discussed my approach and time complexity. The interviewer seemed satisfied and we moved to the next question.

Kth Smallest Element in a Sorted Matrix: I discussed a bunch of solutions and decided that using a min heap would be the best solution. He hinted it could be optimized further. I could not think of a way, so he mentioned binary search, and gave me another hint around it, and then I could solve it.

This round went really well in my opinion. I prefer interviews like this, where the focus is on how you think, how you explore edge cases, build up your reasoning, and adapt with hints. I’d take this kind of discussion any day over an interview where he gets hung up on remembering syntax or using APIs/methods verbatim. This felt collaborative, not combative hahaha, and that makes a world of difference.

Fourth Round – System Design The final round was a system design round to design Instagram. After discussing scope and expectations, we narrowed it down to four main features:

1. Posting content
2. Seeing one's own posts immediately after posting.
3. Feed generation
4. Likes and Comments

I discussed the qualities of the system (non-functional) and set my scale expectations well. From there, I outlined a high-level design and then looked into each of the services. While I covered the core architecture and trade-offs, I realized later that I didn’t allocate enough time to flesh out the likes/comments service fully. I hand-waved a bit near the end as I was short on time.

Result: Rejected on the last round 😞

Outcome & Reflections The process was progressive—I would proceed to the next round only if I cleared the previous. Recruiter mentioned that the team had a meeting to discuss my case, since only the last round was not up to the mark. Ultimately, the feedback on the final round wasn’t strong enough to move ahead.

In hindsight, I could’ve paced the discussion better and spent more time detailing data flow and scaling for likes/comments. I did check with the interviewer throughout to ensure the direction was right—but I missed some depth where it mattered. That said, the round still felt constructive and insightful, had time allowed, I know I could’ve taken it further.