Software Development Engineer-I at Juspay

How it went

What they would tell you

How to prepare

Their background

Round by round

1. 1

   MCQ Round29 min

   In this round, there were 20 questions covering Quantitative Aptitude, Physics, and Computer Fundamentals, including DBMS, CN, DSA, and System Design Principles. Out of these, 2 questions were from Quantitative Aptitude (focused on Data Interpretation) and 2 from Physics (Rotational Motion and Newton’s Laws of Motion). Since I had forgotten most of the Physics concepts, I guessed those answers. The remaining questions were quite straightforward and consisted of well-framed, high-quality CS fundamentals problems.

2. 2

   Coding Test90 min

   This round leaned towards the difficult side, with 3 questions that were definitely of medium to high difficulty level, all based on Graphs and DSU. Before the round, HR mentioned that I needed to score at least 66% to qualify for the next stage. I managed to pass 75% of the total test cases, which made me eligible for the next round.

   • Graphs
   • Disjoint Set Union
3. 3

   Tree Of Space Part A180 min

   This was Juspay’s well-known Tree of Space round, where you need to solve a tree-based problem (which is easily available online). The difficulty level wasn’t too high since ample time was provided to work on it. However, instead of copying solutions from the internet, it’s important to implement your own, as Juspay takes plagiarism very seriously. To qualify for this round, you must pass at least 7 out of 10 test cases.

   • Tree-Based
4. 4

   DSA Interview Round90 min

   In this round, you are required to solve a DSA problem in an online meet setup. The questions are typically from topics like Graphs, Trees, Binary Search, etc. In my case, the problem was based on DSU. The statement was a bit tricky, as it wasn’t immediately obvious that it was a graph problem. I carefully went through the question and clarified each part with the interviewer to show that I was actively trying to understand it. Eventually, I realized it was indeed a graph-based problem. I started by solving it using DFS, dry-ran my approach with a few test cases, and also explained the time complexity. The interviewer was satisfied with both my approach and explanation. After that, I was given a follow-up, which required extending the solution towards DSU. I only needed to explain the approach and dry-run some test cases, without coding. The interviewer seemed happy with my reasoning, and the interview concluded on that note.

   • DSU
   • DFS
5. 5

   Tree of Space Part B360 min

   Now this round is the most extensive round I have ever faced. So this round can easily last whole day. So this round was split up with two sections. Before lunch interviewer asked me about my Part A solution and approach. You have to explain each and every lines of your code in a great details. And this if your code was not the most optimised one then you have to optimised it on the spot In my case my part A solution was O(n) which was not the most optimal one. So then I had to optimise it in O(logN) which was not that hard. After that I was asked to derive the height of a m-ary tree using mathematical derivations. Then I was asked what is DFS and BFS and there basic difference. so after all of this my 1st part was done, Then the interviewer gave me the actual problem statement of part B and told me that we will rejoin the meet and start solving this after lunch break So the problem statement is basically I have to tell whether my solution is thread safe or not. That means whether my current implementation of Tree Of Space can run on a single core multithreaded environment and still don't arise any race condition or violates any core conditions of tree of space. So generally the current implementation was not thread safe. So then I explained the interviewer that why it is not thread safe and in which condition my code arise race conditions. So after that I have to make only one function thread safe which is the lock() function (without any library and all) so after brainstorming a bit I gave a solution and after couple of iterations and correction finally I reached the final thread solution and my interview was wrapped up. One tip for this round . Before this round learn about multithreaded environment, multithreading, race condition so if interviewer gave you hint so you can catch up it. Be calm and also thought out loudly and interact with the interviewer about your thoughts. Don't loose your patience for this round.

6. 6

   Techninal Interview Round180 min

   This round was held on-site at Juspay’s office. It began with a brief introduction where I was asked to talk about myself, the overall project-building process, and what I enjoy most in development.

   The interviewer then moved on to my projects. I explained one of my projects in detail, what I had built, the tech stack I used, and the overall architecture. Following this, I was asked to design a probable schema for my project’s backend. Specifically, I had to:

   • Choose an appropriate database,
   • Justify my choice, and
   • Design the schema on a whiteboard with all the relevant fields and relationships.

   Initially, I missed a couple of fields in the schema, but the interviewer gave hints that helped me refine it. Eventually, I was able to arrive at a more complete design.

   After this, I was given a Low-Level Design (LLD) problem, where I had to design an ATM machine. Since I wasn’t very strong in LLD, I struggled a bit with gathering the requirements and coding the solution. While I did my best to implement it, the code quality and adherence to proper LLD principles were not up to the mark. The interviewer acknowledged my effort, but it was clear that my LLD preparation needed more depth.

   The round concluded after this exercise.

What came up