Confluent Interviews

My friend referred me at Confluent, and I received a callback from the recruiter within two hours. The interview was scheduled three days later and consisted of three technical rounds followed by one Engineering Value round. The technical rounds were scheduled upfront, and based on their outcome, the engineering value round was set up. After clearing all these, I would move to a team matching round and then receive an offer.

Round 1:
This round started very casually with a discussion about my experience before moving straight to the question. I was asked to design an LRU cache with time-to-live (TTL) functionality. The expected operations included adding new key-value pairs with a timestamp, getting key-value pairs, and efficiently calculating the average of all actively stored values. I clarified constraints and expectations initially, asking questions like whether key-value pairs would be given in strictly increasing timestamps. I began with a simple approach and then optimized it based on various considerations such as memory usage, collision handling, performance (read-heavy vs. write-heavy scenarios), and more.

Round 2:
Again, this round began with a brief introduction and a discussion of my experience before moving to a DSA question. I was tasked with implementing my own logging system. Given a log file, I needed to print the last N lines using file methods of my preferred language (I used Python). The interviewer then asked about optimizing this for scenarios with many lines that need continuous printing to the console. I suggested returning the data line by line, and then byte by byte, to conserve program space. Additionally, I had to print the last N lines in their original file order, not reversed, without storing the entire file in memory.

Round 3:
There was no introduction in this round; we immediately delved into a DSA question. I was given the task of implementing a word search functionality within an array of documents. Specifically, I would receive an array where each item was a document with a unique number and complete data. Given a word, I had to find all document numbers where that word was present. The next step was to optimize this by initializing and creating a processed data store format for efficient searching. To improve it further, I was asked to implement phrase search. After asking some clarifying questions, I proposed a solution. The interviewer specifically requested using a single data store created during the preprocessing step that could serve both word and phrase searches. I proposed an approach for this, but due to time constraints, I couldn't fully implement it.

After one week, I received a call informing me that I had cleared the technical rounds and was moving to the Engineering Value round.

Engineering Value Round:
This round focused on my experience, projects, challenges faced, volunteering efforts, mentorships, and team interactions. There was a lot of grilling, which is expected in such rounds.

Approximately 1.5 weeks later, I got a call confirming that I had cleared all rounds and was moving to team matching.

Team Matching Round:
In this round, the manager asked about my experience and then elaborated on the team's work and culture. I asked many questions about these aspects, and the call went well. Three days later, I received a call indicating they were moving forward with an offer. However, two days after that, I was informed that due to a global hiring freeze, the offer letter would be released once the freeze is lifted.