A Backend Engineer at Fi Spills The Beans on His Interview Experience

I got hired as a software engineer at Fi Money, and while preparing for the interviews, I found very few such interview experience explainers online. So, I decided to share my own.
Fi is one of India's fastest-growing fintech startups in India. Simply put, it is an intelligent way to do your banking via an online savings account powered by a licensed partner, Federal Bank! The creators of Google Pay in India: Sumit Gwalani & Sujith Narayanan — are the minds behind Fi.

My Journey to Fi Money

Now, to tell you a bit about me, I completed my BTech in Electronics and Communication Engineering in 2021. I joined Grab for a six-month internship during my final semester and continued for another six months full-time.
At this point, you must be wondering: Why did I leave Grab, one of the leading product-based companies with a great work culture? The reason was that my role as a site reliability engineer did not align with my interests. So, I started looking for opportunities as a backend engineer.
During this time, I received a LinkedIn message from Fi's talent team asking if I was interested in a backend role. I had seen a few ads for the Fi-Federal co-branded credit card — which told the company revolved around banking and finance. I immediately jumped onto the company's LinkedIn profile to learn more and was amazed by their team. Check out this LinkedIn page to see for yourself.
Full disclosure; before getting into my interview experience, I was also in conversation with other companies like IndMoney, Sharechat and Bluestacks and was previously rejected by Amazon and PhonePe. Ok, enough context, let's begin.

The Interview Process at Fi Money

Hackerrank test

After I replied to the message, I was asked to complete a Hackerrank coding test. Brace yourself; it's about to get technical. The test had three coding questions.

*Implementation-based; medium-difficulty
*Based on DP; medium-difficulty
*A hard question on graphs.

It was a combination of cycle detection and multi-source BFS over it. This can be quite difficult if you haven't practised graph concepts. After clearing the test, my first interview round was scheduled with a former Directi engineer, so I expected some tough questions.

Interview Round 1

The round started with introductions and questions about my work at Grab. Then we jumped on to the first question. It was a LeetCode hard problem - binary tree maximum path sum. I was prepared for this and explained it well, and wrote its complete code.
The second question was string-based, where I was asked to find the longest palindromic substring in a given string. I explained the brute force approach first, then the optimised approach and then wrote its code. I tested it on a few test cases, including some edge cases, and it cleared all of them.
There was still some time left, so we discussed one of the projects I worked on at Grab before closing the round.

‍ Interview Round 2

After a few days, I got a call to schedule the next round. This time, the interview was with an Ex-Goldman Sachs, Ex-Flipkart, ICPC Regionalist. After polite introductions, it was onto the first question. It was a typical heap-based question, easy if you are clear with the concepts.
I explained the brute force approach and then the optimised one. Then coded the solution, and it ran on some hidden test cases. It cleared all the test cases in one go, so we moved on to the next question.
The second question was a LeetCode hard problem — the minimum number of taps needed to open in order to water a garden, based on DP and Greedy. I explained the brute force approach first and then considered the optimised approach.
leet codeI got lost trying to solve this, but the interviewer helped me get back on track. I explained the optimised solution, wrote the code and ran it on the hidden test cases. It failed on some test cases, most probably some edge cases.

I spent a lot of time on this question, and only five minutes were left. The interviewer asked me whether I had any questions for him or if I wanted to continue solving the problem. I went with the latter and got a few more edge cases cleared, and we closed that call after that.

At this point, I wasn’t sure I’d get called for the next round.

Interview Round 3

But, I got the call after a few days. I was all the more nervous since they specified that this was not a DS and Algo round. My third interview was scheduled with a founding member of Fi, with almost 15 years of experience, who has worked with tech giants like Netflix, Paypal and Flipkart.
After introductions, the interviewer asked about my previous role at Grab, what I worked on and my projects. There were questions about why I wanted to switch and my expectation from the position at Fi.
Then he asked a simple implementation-based question around hashmap. The intent was probably to check my problem-solving skills, how I approached the question, the code quality, my knowledge of hashmaps, and the data structures used.
I wrote the code, and it worked fine. There were follow-up questions for some more use cases with the intent to check code quality and reusability. I wrote the code with that in mind.
Then we had an engaging discussion on the internals of hashmap, how different types of maps like hashmap and treemap work, and their time complexity. After that, we discussed some of my pet projects.
As the interview ended, the interviewer asked me if I had some questions for him. I asked a few out of curiosity, and he answered them with clarity, and we ended the call there. For the entire interview duration, it never felt like I was speaking to a senior and experienced person. It felt like a very comfortable conversation.

Interview Round 4

After a few days, I got called to schedule the fourth and final interview round with a founding member of Fi. His LinkedIn profile said he had over 12 years of experience at Google alone and was one of the founders of Google Pay. It was supposed to be a techno-behavioural round, so I had no idea what to expect.
Post introductions, he asked questions regarding my current role at Grab, the projects I was working on and why I wanted to switch.
After that, he started getting into computer science fundamentals and asked a few questions about DBMS fundamentals and their practical uses. Then, we briefly discussed the pet projects I mentioned in my resume.
Then came the behavioural questions. The intent was to discover my vision, approach toward problems and how I react to different situations. It was an exciting round, and it never felt like an interview.
Then he asked an obvious question, “Why do you want to join Fi?”.
And just when I thought the interview was almost over, he surprised me with a question based on Heap. It was an easy question which I could answer comfortably. I first explained the brute force approach and then the optimised method using a Heap. He followed that up with some questions about the internals of the Heap.
Finally, he asked if I had any questions. I had been using the Fi app, so I asked a few questions about how things worked on the app. He cleared all my doubts before closing the call.
The interview went quite well, and I expected a positive result. A few hours later, I got the intent/offer mail and breathed a sigh of relief. A month of preparation, interviews, rejections and learnings ended positively.
Thanks to the recruitment team at Fi for making this interview process pleasant and smooth. Check out open roles here.

-As told to Ulfath Joad

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