Revolut Senior Software Engineer Interview Questions and Answers

Q1. Number of subset
Ans. 
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
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Q2. Remove kth node from end
Ans. 
Remove the kth node from the end of a linked list.
• Use two pointers, one to traverse the list and another to keep track of the kth node from the end.

• Once the first pointer reaches the end, the second pointer will be at the kth node from the end.

• Adjust the pointers to remove the kth node.
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Q1. Whatsapp low level design
Ans. 
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
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Q2. Lru implemention
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Q1. Longest Consecutive Sequence
Ans. 
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
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Q2. Core Java Questions
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Q1. Executor Service and it's code
Ans. 
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
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Q2. Core Java and Spring boot questions
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Q1. Design patterns
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Q2. Core Java questions
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Was a tough oneto crack

Q1. Asked about core Java domain and threds
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Q2. Asked about Java domain and threads collection
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Q3. Threads and collection
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Asked to do coding for RDBMS using any programing language

Q1. Machine coding: Design in-memory document search
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Q1. HLD: Design a ad-click aggregation service
Ans. 
Design an ad-click aggregation service for tracking and analyzing ad clicks.
• Use a distributed system to handle high volume of ad click data

• Implement real-time processing for immediate insights on ad performance

• Utilize a database to store aggregated ad click data for reporting and analysis
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Q1. Design a in-memory cache
Ans. 
Design a high-performance in-memory cache system for storing and retrieving data efficiently.
• Use a hash table or a key-value store to store data in memory

• Implement caching strategies like LRU (Least Recently Used) or LFU (Least Frequently Used) to manage cache eviction

• Consider using a distributed cache for scalability and fault tolerance

• Optimize cache size and expiration policies based on the application's data access
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Q1. Rating Service Low level design
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