Juspay - Software Development Engineer (SDE)

The first round was an online coding assessment of 90 minutes with three graph-based problems. I was able to fully solve two problems and partially solve the third. The level of difficulty was medium to hard. Interestingly, the problems seemed similar to ones asked in their previous drives, which gave an impression that Juspay doesn’t frequently update their question bank. Despite not completing all questions, I cleared this round.

In this round, I was given one graph-related problem called “Tree of Space” with a 90-minute time limit. The task involved more than just solving the problem – I had to carefully analyze and explain the time and space complexities of my solution. The interviewer then shifted focus towards concurrency. I was specifically asked to make the locking mechanism of my code thread-safe, but interestingly, I was told not to use common tools like mutex or semaphores. This forced me to think deeply about possible inconsistencies that might occur when multiple threads access shared resources. I explained different scenarios of race conditions and inconsistencies, and eventually implemented a rollback-based mechanism to handle them. The interviewer was patient, gave hints when I was stuck, and overall the discussion was technical but friendly. I cleared this round successfully.

This was more of an all-day problem-solving session rather than a typical interview. I was asked to continue working on the same “Tree of Space” problem, but with deeper emphasis. The round focused on:

Deriving and justifying optimal approaches. Ensuring thread safety in more complex scenarios. Handling concurrency issues with rollback mechanisms.

The interviewer actively engaged with me, sometimes challenging my approach, but also guiding me when I was stuck. It felt like a collaborative problem-solving session. This round was mentally exhausting but very insightful, and I managed to clear it as well.

This was the most unusual and frustrating part of the process. I was asked to travel to their Bangalore office for the final two rounds. When I arrived, there were several candidates present. Instead of typical coding/system design rounds, we were all given non-computer science problem statements like:

“You are given a coil, magnets, shaft, wheel, and battery. How would you build a motor?” “You are given a piston, gears, heat/cold input, and wheels. How would you build a steam engine?”

We were not allowed to use our phones or external resources, so it basically came down to recalling high-school physics. From 11 am to 5 pm, we worked on these questions and presented our reasoning.

Later in the evening, around 5:30 pm, the one-on-one interviews finally started. Each candidate was being interviewed for over an hour, but despite waiting till 8 pm, I was never called in. Finally, I (and one other candidate) were informed that the process was over and we could leave. This left me extremely disappointed, since I had spent the entire day waiting without even being given a fair chance.