36 questions · from 6 interviews
Confluent interview questions
Every question candidates reported from their Confluent interviews, most frequently asked first. Each links to the write-up it came from, so you can see the round and how it went.
Confluent coding and DSA questions
- 01
Sudoku Verification
Verify whether a given Sudoku board is valid according to Sudoku rules (no duplicate numbers in rows, columns, or 3x3 sub‑grids).
From Confluent (IBM) | Software Engineer - L2 | 2.5 YoE | Rejected
- 02
Sudoku Solver
Solve a partially filled Sudoku board by filling in digits so that the board becomes a valid completed Sudoku puzzle.
From Confluent (IBM) | Software Engineer - L2 | 2.5 YoE | Rejected
- 03
Find Word in Document List
Given a list of document strings, locate a specific word across the documents and return its position(s).
From Confluent (IBM) | Software Engineer - L2 | 2.5 YoE | Rejected
- 04
Find Phrase in Document Sequence
Given a list of document strings, find a phrase that appears in the same sequential order across the documents and return its occurrence details.
From Confluent (IBM) | Software Engineer - L2 | 2.5 YoE | Rejected
- 05
Implement Unix 'tail -n' Command
Implement unix 'tail -n' command to print last n lines of a file. Concurrency handling was not required. There were follow ups related to memory and time complexity optimization. Running optimal code was required.
Medium · From Confluent | Senior Software Engineer | Rejected
- 06
Subset Sum for Bank Transactions
Given a list of numbers, each representing a bank account transaction (positive for credit and negative for debit) your task it to tell if there exists a sequence of transactions which can lead to a given balance amount. Started with O(n^n) brute force…
Hard · From Confluent | Senior Software Engineer | Rejected
- 07
Document Search with Keyword
Given a list of doc and a query string, return which documents contain the query string in it. Input: [][]string{ {"this", "is", "world"}, {"world", "is", "great"}, {"leetcode", "is", "bad"} } query("World") -- should return [0,1] (make sure your search is…
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- 10
Design Queue with Enqueue, Dequeue, GetRandom
Design a queue that support enqueue, dequeue and getRandom() operations. Follow up included concurrency. What will happen if multiple threads are working together? What are the solutions available to support multiple threads?
- 11
Compare Two Queues with Concurrency
Write method to compare two given queues. Again, follow ups were about support concurrency in this method.
- 12
Design LRU Cache with TTL and Average Active Values
Design an LRU cache that supports Time-To-Live (TTL) for its entries. The cache should implement operations to: Add a new key-value pair along with its time. Retrieve a key-value pair. Efficiently calculate the average of all currently active values in the…
From [Offer] [Hiring freeze] - Conflunt SSE - India Interview experience
- 13
Implement Logging System: Print Last N Lines (and in order)
Implement a custom logging system. Given a log file, the primary task is to print the last N lines. This problem must be solved using file methods available in the programming language of choice (I used Python). Further optimizations were discussed, such as…
From [Offer] [Hiring freeze] - Conflunt SSE - India Interview experience
- 14
Implement Document Word and Phrase Search Engine
I was given the task to implement a word search functionality across an array of documents. Each document has a unique document number and its complete data. Given a specific word, the system should identify and return all document numbers where the word is…
From [Offer] [Hiring freeze] - Conflunt SSE - India Interview experience
- 15
Match Function Signatures to Arguments
Given a list of function signatures and a list of input arguments, return all matching functions based on parameter compatibility. Extend the solution to handle variadic arguments like Integer... args . Focus was on type matching and signature parsing.
From Confluent Interview Experience| SSE2 | May 2025 | No Offer
- 16
Validate Sudoku Board
Check if a given Sudoku board is valid (partial board). Emphasis was on clean recursion, backtracking, and pruning optimization.
From Confluent Interview Experience| SSE2 | May 2025 | No Offer
- 17
Solve Sudoku Puzzle
Solve a complete Sudoku puzzle. Emphasis was on clean recursion, backtracking, and pruning optimization.
From Confluent Interview Experience| SSE2 | May 2025 | No Offer
- 18
Debug and Optimize Quicksort
Given an implementation of Quicksort , identify and fix bugs. Then optimize performance by discussing and applying pivot strategies to reduce the chance of hitting O(n²). Strategies covered: Randomized pivot Dual pivot Median-of-three approximation
From Confluent Interview Experience| SSE2 | May 2025 | No Offer
- 19
Key-value Store with Expiration and Average
Design a key-value store with expiration. It should support the following functions: put(key, value) , get(key) , and getaverage() (which returns the average of all non-expired values). Data is streamed in order of increasing timestamps.
- 20
Word and Phrase Search in Documents
Implement a system for word and phrase search within a given list of documents.
- 21
Validate and Solve Sudoku
Given a Sudoku puzzle, write functions to validate if it's correct and to solve it.
Confluent system design questions
- 01
Design Podcast Aggregator
Create an aggregator that allows podcasts to be registeres and users to subscribe/unsubscribe different podacasts. I was asked to write APIs required for it and different HTTP status code that our API can support. Make sure you know when to return what http…
Hard · From Confluent Onsite | India
- 02
Design Temporary Email Service with TTL
Create a temp email service with TTL of 5 hours per email. How to generate unique emails that are not too long. What kind of DB to store the create the emails? How will access be denied once the email id expires? Discuss Data archival once the emails are…
Hard · From Confluent Onsite | India
- 03
Design a Podcast Service
Design a Podcast Service with: Feed view Subscribe/Unsubscribe to podcasts Add podcasts and episodes No architecture diagram was expected. Focus was on: API design (verbs, response codes, headers) SQL queries Data modeling
From Confluent Interview Experience| SSE2 | May 2025 | No Offer
- 04
Design a TempMail Service
Design a TempMail generation service where generated emails are valid for 5 hours . Discussion focused on: Expiry mechanism Storage strategies Access control and validation Building sensible mail names
From Confluent Interview Experience| SSE2 | May 2025 | No Offer
- 05
URL Shortener Design
Design a URL shortener. The design should focus on scalability, system reliability, database and cache sharding strategies, and resource calculations (e.g., Requests Per Second (RPS), memory, number of servers). Discuss the pros and cons of multiple…
- 06
Design a Newsfeed System (Feedly-like)
Design a system similar to Feedly. The design should focus on API design and data modeling for features such as user subscriptions/unsubscriptions and efficient newsfeed generation.
Confluent behavioural and HR questions
- 01
Exceeding Customer Expectations
Discuss going above and beyond to exceed customer expectations .
From Confluent Interview Experience| SSE2 | May 2025 | No Offer
- 02
Taking Initiative in Challenging Situations
Discuss taking initiative in challenging situations .
From Confluent Interview Experience| SSE2 | May 2025 | No Offer
- 03
Pushing Back on Legacy Decisions
Discuss pushing back on legacy decisions and suggesting improvements.
From Confluent Interview Experience| SSE2 | May 2025 | No Offer
- 04
Mentoring and Enabling Peers
Discuss mentoring and enabling peers to succeed.
From Confluent Interview Experience| SSE2 | May 2025 | No Offer
- 05
Handling Ambiguity and Complexity
Discuss handling ambiguity and overcoming complexity in large-scale systems.
From Confluent Interview Experience| SSE2 | May 2025 | No Offer
- 06
Confluent Values Behavioral Questions
Behavioral questions aligned with Confluent's core values, aimed at assessing cultural fit and past experiences relevant to the company's principles.
- 07
Team Match and Motivations Discussion
A discussion similar to a team match call, covering aspects of teamwork, personal interests, career motivations, and how they align with potential teams.
Confluent other questions
- 01
Football Club Revenue Analysis (API & Pricing)
Analyze potential revenue for football (soccer) clubs based on their stadium capacity and historical performance. Use HTTP GET requests to access a football club database via the URL: ---a mock endpoint was provided----/footballteams?league={leaguename} with…
- 02
Write Unit Tests for Queue Operations
Write UTs for the enqueue, dequeue and getRandom(). They just wanted to get idea about UT techniques.
Confluent interview questions FAQ
What questions are asked in Confluent interviews?
Candidates reported 36 distinct questions across 6 Confluent interviews. 21 coding and DSA questions, 6 system design questions, 7 behavioural and HR questions, 2 other questions.