Instawork India Senior Software Engineer Interview Questions and Answers

Given an simple gaming questions to be developed in JS

Given another UI design in image to be developed

Q1. What is event loop, how it works.
Ans. 
Event loop is a mechanism in programming that allows for asynchronous execution of code by continuously checking for and handling events.
• Event loop is commonly used in JavaScript to handle asynchronous operations like setTimeout, setInterval, and AJAX requests.

• It works by continuously checking the event queue for any pending events, executing them one by one, and then moving on to the next event.

• Event loop helps in pre...read more
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Q2. Micro task queue and macro task queue.
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Q3. Is node.js single threaded or multi-threaded, also discuss threadpool and it's usages.
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Q4. Tell the order of output, among process, promise, setTimeout, fs, setInterval.
Ans. 
The order of output is fs, process, setTimeout, setInterval, promise.
• fs module is synchronous and will output first

• process is next in line

• setTimeout will be executed after process

• setInterval will be executed after setTimeout

• promise will be executed last
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Q1. JavaScript usages compiler or interpreter.
Ans. 
JavaScript is an interpreted language.
• JavaScript is an interpreted language, meaning it is executed line by line at runtime.

• There is no separate compilation step in JavaScript like in languages that use compilers.

• Examples of interpreted languages include Python, Ruby, and PHP.
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Q2. Tell the output among various for loops using var, let and bind.
Ans. 
Output comparison of for loops using var, let, and bind in JavaScript.
• Using var: variable is function-scoped, may lead to unexpected behavior in loops.

• Using let: variable is block-scoped, recommended for loop iterations.

• Using bind: creates a new function with a specified 'this' value and initial arguments.
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Q3. A medium level dsa question on array, solved it using pre-sum.
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Q4. Situation based question, on how to pick a suitable database.
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Q1. What do you do on daily basis, and how to decide a tech-stack on high level.
Ans. 
I work on coding, debugging, testing, and collaborating with team members. Tech stack decisions are based on project requirements, scalability, performance, and team expertise.
• Daily tasks include coding, debugging, testing, and collaborating with team members

• Tech stack decisions are based on project requirements, scalability, performance, and team expertise

• Consider factors like language compatibility, libraries/framewo...read more
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Q2. Design an online scalable, real-time document sharing application like google docs.
Ans. 
Design a scalable, real-time document sharing app like Google Docs.
• Use websockets for real-time collaboration

• Implement version control to track changes

• Utilize a distributed database for scalability

• Include user authentication and access control

• Support offline editing with automatic sync
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Q3. How to handle images also in the future.
Ans. 
Utilize cloud storage for scalability, implement image compression techniques, and regularly update image processing libraries.
• Utilize cloud storage for scalability

• Implement image compression techniques

• Regularly update image processing libraries
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Q4. Any other way to solve the problem, of high I/O on same document to overcome throughput and conflicts.
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Q1. Create a controller , service and repository methods and classes to save userDeatils in table using Spring Data JPA .
Ans. 
Create a controller, service, and repository to save user details using Spring Data JPA.
• Create a UserController class with appropriate mappings for saving user details.

• Create a UserService class with a method to save user details.

• Create a UserRepository interface that extends JpaRepository to handle database operations.

• Implement the saveUserDetails method in the UserService class to call the save method of the UserRepo...read more
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Q1. Basic java 8 concepts
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Q2. Basic spring boot questions
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Q1. Project discussion and basic java spring technical questions
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Q1. Design Splitwise Application (LLD)
Ans. 
Design a Splitwise application for managing shared expenses among friends.
• Implement user authentication and authorization for secure access.

• Create a user-friendly interface for adding expenses and splitting them among friends.

• Develop algorithms for calculating balances and settling debts between users.

• Include features for adding comments, attaching receipts, and generating reports.

• Consider scalability and performance o...read more
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Q1. Template and Reactive Forms in Angular
Ans. 
Template and Reactive Forms in Angular are two ways to handle forms in Angular applications.
• Template Forms are based on the traditional HTML forms and are easy to use for simple forms.

• Reactive Forms are more flexible and powerful, allowing for complex form validation and dynamic form controls.

• Template Forms use two-way data binding, while Reactive Forms use a more reactive approach with observables.

• Reactive Forms are r...read more
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Q1. Replace all zeros to 1 which are surrounded by 1's
Ans. 
Replace zeros surrounded by ones with ones in an array of strings
• Iterate through each string in the array

• Check for zeros surrounded by ones and replace them with ones

• Return the modified array of strings
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Q2. Minimum jumps to reach end of an array
Ans. 
The minimum number of jumps needed to reach the end of an array.
• Use dynamic programming to keep track of the minimum jumps needed at each index.

• At each index, calculate the maximum reachable index and update the minimum jumps accordingly.

• Example: For array [2, 3, 1, 1, 2, 4, 2, 0, 1, 1], the minimum jumps needed is 4.
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Q1. LLD Round:- Design classes for bidding system when new bid notifications shown to all users who already bided for it.
Ans. 
Design classes for a bidding system with new bid notifications for users who have already bid.
• Create a Bid class with attributes like bidder, amount, timestamp, etc.

• Create a Notification class with attributes like message, recipient, timestamp, etc.

• Create a BiddingSystem class to manage bids and notifications.

• Implement a method in BiddingSystem to notify users who have already bid when a new bid is placed.

• Consider usin...read more
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Q2. HLD:- Desing Post order service, or last mile like finding rider, notifications etc
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Q1. Design LLD of google calendar
Ans. 
Design LLD of google calendar
• Use microservices architecture for scalability and maintainability

• Implement features like event creation, editing, deletion, reminders, and sharing

• Utilize databases for storing user data and events

• Include user authentication and authorization for security

• Integrate with external APIs for syncing with other calendars
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