Visa Senior Data Scientist Interview Questions and Answers

Q1. What is java multithreading
Ans. 
Java multithreading is a feature that allows concurrent execution of multiple threads within a single process.
• Multithreading in Java allows multiple threads to run concurrently within a single process.

• Each thread has its own stack and executes independently, but shares the same memory space.

• Java provides built-in support for multithreading through the java.lang.Thread class and java.lang.Runnable interface.

• Multithreadi...read more
Answered by AI
Add your answer
Q2. Explain exception hierarchy
Ans. 
Exception hierarchy is a way to organize and categorize different types of exceptions in a software system.
• Exceptions are organized in a tree-like structure with a base class at the top and more specific exception classes below.

• Base class usually is 'Exception' or 'Throwable', with more specific classes like 'IOException', 'NullPointerException', etc.

• Subclasses can provide more specific information about the cause of t...read more
Answered by AI
Add your answer

Android topics and basics of DSA. Coding question related to DSA medium level.

Android topics and basics of DSA. Coding question related to DSA medium level.

This was taken by manager and included topics related to security and few concepts/practices implementation in Android/ Google architecture like firebase messaging deep diving, crashlytics deep diving and its working, etc. Coding question related to DSA medium level.

Q1. Pure salary bargaining round.
Add your answer

Q1. An array based problem about sorting and stock price calculation.
Add your answer

Q1. A binary tree related question to calculate height.
Add your answer

Q1. API creation, authentication and JWTs
Add your answer

Hackerrank Online Coding test. DSA Questions

Q1. Create Traffic Lights in react.js with lights changing color with time config
Ans. 
Create a traffic light simulation in react.js with changing colors based on time configuration.
• Use React state to manage the current color of the traffic light

• Set up a timer to change the color of the traffic light at specified intervals

• Use CSS to style the traffic light and different colors for each light
Answered by AI
Add your answer
Q2. Polyfills of map, reduce, call, apply
Ans. 
Polyfills are used to provide fallback support for older browsers that do not support certain JavaScript methods like map, reduce, call, and apply.
• Polyfills are JavaScript code that replicate the functionality of newer features in older browsers.

• They are commonly used for methods like map, reduce, call, and apply which may not be supported in all browsers.

• For example, a polyfill for the map method would involve iterati...read more
Answered by AI
Add your answer
Q3. Other Javascript concept questions like closures, teporal dead zone, let const var difference, arrow function vs normal function
Add your answer

Q1. Web app Optimization Techniques
Ans. 
Web app optimization techniques focus on improving performance and user experience.
• Minify and compress CSS, JavaScript, and HTML files

• Optimize images and use lazy loading

• Reduce server response time by caching data and using CDNs

• Implement asynchronous loading for non-essential resources

• Use browser caching and enable Gzip compression
Answered by AI
Add your answer
Q2. Javascript optimzation tehniques
Add your answer
Q3. Infinite scroll - how to handle large size data, efficient and smooth loading by scrolling up & down.
Ans. 
To handle large size data for infinite scroll, use virtual scrolling, lazy loading, and optimize data fetching/rendering.
• Implement virtual scrolling to render only the visible items on the screen, reducing memory usage and improving performance.

• Use lazy loading to fetch more data as the user scrolls, avoiding loading all data at once.

• Optimize data fetching and rendering by using efficient algorithms and data structures...read more
Answered by AI
Add your answer
Q4. Serverside vs clientside rendering
Ans. 
Serverside rendering is when the HTML is generated on the server before being sent to the client, while clientside rendering is when the HTML is generated on the client's browser using JavaScript.
• Serverside rendering is better for SEO as search engines can easily crawl the content.

• Clientside rendering can provide a faster initial load time as only data is sent from the server.

• Serverside rendering is more secure as sens...read more
Answered by AI
Add your answer
Q5. Microservices vs Monolithic architecture
Ans. 
Microservices allow for modular and scalable architecture, while monolithic architecture is simpler but less flexible.
• Microservices break down applications into smaller, independent services that communicate through APIs.

• Monolithic architecture involves building the entire application as a single unit, making it easier to develop but harder to scale.

• Microservices offer better fault isolation and scalability, while mono...read more
Answered by AI
Add your answer
Q6. How to acheive responsive acrooss all screen sizes
Ans. 
Achieve responsive design by using media queries, flexible layouts, and fluid grids.
• Use media queries to adjust styles based on screen size

• Create flexible layouts that adapt to different screen sizes

• Implement fluid grids to ensure content scales proportionally
Answered by AI
Add your answer

Q1. Salary discussion
Add your answer

Sort an array of 0s, 1s and 2s, Design a music player with shuffle functionality: output- int[] with shuffled

Reversing a linked list in groups, diagonal traversal of BT

Q1. Bookmyshow HLD , Write a Mysql query to get the 3rd Highest salary.
Add your answer

Q1. General discussion
Add your answer

Some mcq questions on Java and 2 DSA medium questions

Q1. Spring boot , Java and DSA questions
Add your answer

Q1. Design BookMyShow low level design
Ans. 
BookMyShow low level design for ticket booking system
• Use microservices architecture for scalability and flexibility

• Implement user authentication and authorization for secure transactions

• Utilize databases for storing user and event information

• Include payment gateway integration for seamless transactions
Answered by AI
Add your answer

Q1. Design lru cache and code
Ans. 
LRU cache is a data structure that stores a fixed number of items and removes the least recently used item when the cache is full.
• Use a combination of a doubly linked list and a hashmap to implement the LRU cache.

• When an item is accessed, move it to the front of the linked list to mark it as the most recently used item.

• When adding a new item, check if the cache is full. If it is full, remove the least recently used ite...read more
Answered by AI
Add your answer

Q1. Sharding, sql vs nosql, project discussion and tradoffs
Add your answer

Q1. Behavior and culture questions
Add your answer

Q1. Create useDebounce hook
Ans. 
Custom hook for debouncing user input in React applications
• Accepts a value and delay as arguments

• Uses useEffect to set a timeout to update the debounced value after the specified delay

• Returns the debounced value and a function to update the input value
Answered by AI
Add your answer
Q2. Create language change functionality using useContext and useReducer
Ans. 
Implement language change functionality using useContext and useReducer
• Create a LanguageContext to store the current language state

• Use useReducer to handle state changes for language selection

• Dispatch actions to update the language state based on user selection
Answered by AI
Add your answer