Mobikwik Senior Software Engineer Interview Questions and Answers

Calculate the number of subsets of a given set

• The number of subsets of a set with n elements is 2^n

• Include the empty set and the set itself in the count

• For example, a set with 3 elements will have 2^3 = 8 subsets

Whatsapp low level design involves messaging, encryption, media sharing, and user authentication.

• Use end-to-end encryption to secure messages

• Implement message queues for real-time message delivery

• Allow media sharing through file transfer protocols

• Use OAuth for user authentication and authorization

Find the length of the longest consecutive elements sequence in an array.

• Sort the array to ensure consecutive elements are adjacent

• Iterate through the array and keep track of the current consecutive sequence length

• Update the longest consecutive sequence length as you iterate

Executor Service is a framework provided by Java for managing and executing asynchronous tasks.

• Executor Service allows you to easily create and manage threads for executing tasks.

• It provides a way to control the number of threads used for executing tasks, which can help prevent resource exhaustion.

• You can submit tasks to an Executor Service using methods like execute() or submit().

• Executor Service can be used to execut...read more

Design a scalable task scheduler to manage and execute tasks efficiently based on priority and timing.

• Define task attributes: ID, priority, execution time, and status.

• Use a priority queue to manage task scheduling based on priority.

• Implement worker threads to execute tasks concurrently.

• Consider persistent storage for tasks to survive system restarts.

• Provide an API for adding, updating, and removing tasks.

I have extensive experience in software development, focusing on scalable applications and team collaboration.

• Led a team of 5 developers in creating a microservices architecture for a healthcare application, improving scalability by 40%.

• Implemented CI/CD pipelines using Jenkins and Docker, reducing deployment time from hours to minutes.

• Collaborated with cross-functional teams to gather requirements and deliver features...read more

Implement rate limiting for a platform serving 100K requests per second.

• Use a token bucket algorithm to limit the rate of incoming requests.

• Set a maximum number of tokens in the bucket to control the rate.

• Refill the bucket at a constant rate to allow bursts of requests.

• Track the timestamp of the last request to enforce the rate limit.

• Consider using a distributed rate limiting system for scalability.

• Monitor and adjust t...read more

A rate limiter controls the number of requests a user can make to a service in a given timeframe.

• Use a token bucket algorithm to allow bursts of requests while enforcing a limit over time.

• Implement a sliding window counter to track requests in a specific time frame.

• Consider using Redis for distributed rate limiting across multiple servers.

• Example: Limit to 100 requests per minute per user.

• Use HTTP headers to inform use...read more

In-memory SQL databases store data in memory for faster access and processing.

• In-memory databases keep all data in RAM for quicker retrieval compared to disk-based databases.

• Examples include SQLite in-memory database and Redis.

• They are commonly used for caching, real-time analytics, and temporary data storage.