10+ Visa Senior Software Engineer Interview Questions and Answers

Count the number of ways to reach target from source in a grid with 0s and 1s.

• Use dynamic programming to solve the problem efficiently.

• Traverse the grid using DFS or BFS to count the number of ways.

• Consider edge cases like when source and target are the same or when there is no path.

• Example: Given grid = [[0,0,0],[0,1,0],[0,0,0]], source = (0,0), target = (2,2), answer is 2.

• Example: Given grid = [[0,1],[0,0]], source = (0,0), target = (1,1), answer is 1.

Tech stack for designing a scalable Uber-like service.

• Use microservices architecture for scalability and fault tolerance.

• Choose a cloud provider with auto-scaling capabilities.

• Use a load balancer to distribute traffic across multiple instances.

• Use a NoSQL database for high availability and scalability.

• Use message queues for asynchronous communication between services.

• Use containerization for easy deployment and management.

• Use caching to improve performance.

• Use monitoring and ...read more

Design a service to aggregate multiple sources of data/documentation centrally.

• Identify sources of data/documentation

• Determine data aggregation method

• Design a centralized database to store aggregated data

• Develop a user-friendly interface to access the data

• Ensure data security and privacy

To scale a monolith architecture and improve response time, use horizontal scaling and implement caching.

• Implement horizontal scaling by adding more instances of the monolith application behind a load balancer

• Use a distributed cache to store frequently accessed data and reduce database queries

• Implement caching at different levels such as application-level caching, database query caching, and HTTP response caching

• Use a caching strategy based on the data access patterns and exp...read more

Merge two sorted arrays into the first array

• Start from the end of both arrays and compare elements

• Place the larger element at the end of the first array

• Continue this process until all elements are merged

Design a cache class with get(), put(), and initialization methods.

• Define a class with a data structure to store key-value pairs.

• Implement a get() method to retrieve a value from the cache based on a given key.

• Implement a put() method to add or update a key-value pair in the cache.

• Implement an initialization method to set the initial capacity and eviction policy of the cache.

• Consider using a hash map or a linked list to store the key-value pairs efficiently.

• Handle cache size ...read more

Custom data structure for array of strings

• Use a trie data structure to efficiently store and search for strings

• Implement methods for adding, removing, and searching for strings in the trie

• Consider optimizing the trie for memory usage and performance

Understanding internal workings of DB structures and indices is crucial for optimizing database performance.

• DB structures refer to how data is organized within a database, such as tables, columns, and relationships.

• Indices are data structures that improve the speed of data retrieval operations by providing quick access to specific data values.

• Understanding how indices work can help in optimizing query performance by reducing the number of rows that need to be scanned.

• Common t...read more

Spring Boot API endpoint is a URL that exposes the functionality of a web service.

• API endpoints are the entry points for the client to access the server's resources.

• Spring Boot provides a simple and easy way to create RESTful APIs.

• Endpoints can be secured using Spring Security.

• Endpoints can be documented using Swagger or Spring REST Docs.

• Examples: /users, /products, /orders

A timer can be implemented using a combination of system time and a loop that checks for elapsed time.

• Get the current system time at the start of the timer

• Enter a loop that continuously checks the difference between the current system time and the start time

• When the desired time has elapsed, perform the desired action or trigger an event

useEffect is a hook in React that allows you to perform side effects in functional components.

• useEffect is used to handle side effects in React components.

• It takes two arguments: a function and an optional array of dependencies.

• The function inside useEffect is executed after the component renders.

• The optional array of dependencies determines when the effect should run.

• If the array of dependencies is empty, the effect runs only once after the initial render.

• If the array of dep...read more

Built a react feature

• Identify the specific feature to be built

• Design the component hierarchy and state management

• Implement the feature using React components and hooks

• Test the feature for functionality and user experience

• Refactor and optimize the code for performance