OLA | SDE 1 | Pune/Banglore

I applied for the SDE 1 role at OLA through a referral. My background includes a B.Tech in Computer Science from a Tier 3 institution, with 1 year of prior experience at a startup.

Online Test on Moocha

I received the online test link and Round 2 invitation simultaneously. The test lasted 60 minutes and consisted of:

• SQL (5 mins): An easy SQL question based on joins, where I had to find the max value from a given schema.
• 3 Coding questions (55 mins): These were of easy-medium difficulty. One was based on LIS, another involved easy array manipulation, and the third was a DP-based question. I managed to solve the first two questions completely. A minor issue was that the platform only supported Java and Python, whereas I usually code in C++.

Round 2 - PSDS (Problem-solving and Data Structure)

This round was 45 minutes long, and I was asked three questions:

1. Shuffle Songs Without Repetition: I was asked how I would play a list of songs randomly such that no song repeats. My initial thought was a brute-force solution using random number generation. For the follow-up, "Can you do it in constant space?", after receiving some hints, I came up with a solution:

   for i from n to 1
     r = random number from (1 to i)
     play the song
     swap the song with ith song
   

   I was asked to code it, but I forgot the exact C++ random syntax, so I used a pseudo-random generator.
2. Consecutive Numbers Summing to N: The problem was to find sets of consecutive numbers summing up to a target n, for example, [2,3,4] and [4,5] for n=9. I began explaining a solution using the formula Sum = n*(n+1)/2, but the interviewer asked for a brute-force approach first. I explained the brute force and then offered a few optimizations.
3. Area Under Histogram Variation: This was a variation of the famous LeetCode "Largest Rectangle in Histogram" problem. I started with a brute-force explanation. The interviewer then prompted me to optimize using a different data structure, so I explained the stack-based solution. When asked how I identified the use of a stack, I elaborated on the concept of a monotonic stack. I was not required to code this problem.

Towards the end of this round, I was also asked "Why do I want to leave my current organization?"

Round 3 - Design Round

In this round, I was asked to design a movie ticket booking site/app, similar to BookMyShow. The discussion was very high-level, focusing on my approach and answering follow-up questions. No coding was involved.

Round 4 - Hiring Manager Round

During this round, two interviewers accidentally joined at the same time, which initially confused me. However, one interviewer was very friendly, introduced himself, and helped me feel comfortable.

• I was asked to introduce myself and discuss my projects. The interviewer reviewed my resume, and then the rest of the interview involved me explaining my projects and previous work in detail.
• Since I remembered every detail of my projects, including class names, the interviewer seemed impressed. He then shifted to asking about my other interests and hobbies.
• With about 15 minutes remaining, I was given a problem that was a variation of the DNF sort. The interviewer asked about the rationale behind using three pointers and the core idea of DNF sort.

I received an email today stating that they are moving forward with my candidature, and I am currently awaiting an official offer. I was also curious about the work culture and work-life balance at OLA, as I'm leaving my current company due to a poor work-life balance.

Outcome: I ultimately declined the offer as I received a better one.