Round 1 covered merge sort optimization, rate limiter design, Course Schedule DSA, Go/SQL/CAP concepts

I got a chance to interview at Zomato. I have heard they are very selective about the people they interview. So I was fortunate enough to get my resume shortlisted there.
Current Exp - 14 months in a startup
HR told me there would be 3 rounds - 2 technical, 1 onsite (Gurgaon)

Round 1

We discussed something about my experience and our deployment strategies.
Then he asked me about merge sort. How it works and what's the time complexity?
If I had 8 core cpu, how would we modify the merge sort for a huge array and what would be the time complexity then?
Then he gave me multiple situations for normal vs modified merge sort algorithm that I gave. I had to order the situations by how much time it would take to sort the array in 1 core vs 8 core cpu.

Then he asked me to implement a rate limiter. I gave a solution using leaking bucket algorithm. He asked me to optimize it for scaling. I gave some approaches but couldn't achieve the optimized solution.

Then we moved to DSA.
https://leetcode.com/problems/course-schedule/description/ - I coded the solution using topological sort.

Then there were multiple questions -

1. Mutex vs Channels (Golang)
2. RWMutex vs Mutex
3. SQL vs NoSQL
4. Why it is difficult to scale in SQL?
5. Why people use SQL vs NoSQL? Discussed about CAP theorem and examples where to use consistency vs availability

Next day I got a call for the next round.

I already had another offer that I accepted from Confluent -
https://leetcode.com/discuss/compensation/5754364/Confluent-or-Software-Engineer-or-Remote

I had another offer from Zepto -
https://leetcode.com/discuss/interview-experience/5763474/Zepto-or-Software-Engineer-or-Bengaluru-or-September-2024-or-Offer

So I just asked them I couldn't move forward in the process.