CoinSwitch Technical Operations Engineer Interview Questions and Answers

Q1. Have you ever faced OutOfMemoryError? How did you resolve that?
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Q2. How you will load text data into DB systems?
Ans. 
Text data can be loaded into DB systems using various methods such as SQL INSERT statements, bulk loading, or ETL processes.
• Use SQL INSERT statements to insert text data into the database one record at a time.

• For large datasets, consider using bulk loading techniques like BULK INSERT or LOAD DATA INFILE.

• ETL (Extract, Transform, Load) processes can be used to extract text data from different sources, transform it as per...read more
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Q1. What are OOPS concepts
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OOPS concepts refer to Object-Oriented Programming principles like Inheritance, Encapsulation, Polymorphism, and Abstraction.
• Inheritance: Allows a class to inherit properties and behavior from another class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Polymorphism: Ability to present the same interface for different data types.

• Abstraction: Hiding the complex implementation detail
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Q2. What are solid Concept
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Solid concepts are fundamental principles or ideas that are well-established and widely accepted in a particular field.
• Solid concepts provide a strong foundation for further learning and development.

• They are essential for understanding complex topics and solving problems effectively.

• Examples of solid concepts in software engineering include object-oriented programming, design patterns, and data structures.
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Q3. Write Code for Palindrome String
Ans. 
Code to check if a string is a palindrome or not.
• Iterate through the string from both ends and compare characters.

• Use two pointers, one starting from the beginning and one from the end.

• If characters at both pointers are equal, move both pointers towards the center.

• If characters at any point are not equal, return false.

• If both pointers meet in the middle, return true as the string is a palindrome.
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Q1. Circle process related questions
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Q2. Scripting language questions
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Q1. What is dependency injection
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Dependency injection is a design pattern in which components are given their dependencies rather than creating them internally.
• Dependency injection helps in achieving loose coupling between classes.

• It allows for easier testing by providing mock dependencies.

• There are three types of dependency injection: constructor injection, setter injection, and interface injection.
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Q2. What is state in react
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State in React is a JavaScript object that stores data and determines how a component renders and behaves.
• State is mutable and can be updated using the setState() method

• State should be used for data that will change over time and affect the component's rendering

• State should not be modified directly, use setState() instead
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Machine coding round, try to come up with at least one working requirement

Q1. Low level design
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Q2. Cant share the exact quesy
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Q1. High level design
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Q1. Hiring manager round
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Q1. Which programming language would you use in which situation?
Ans. 
I would use Python for data analysis, Java for enterprise applications, and JavaScript for web development.
• Python - data analysis, machine learning, scientific computing (e.g. pandas, numpy)

• Java - enterprise applications, backend development (e.g. Spring framework)

• JavaScript - web development, front-end development (e.g. React, Angular)
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Create a service to assign a delivery operator

Q1. Design Uber ride assignment system
Ans. 
Design a system for assigning Uber rides efficiently and fairly
• Use a matching algorithm to pair riders with drivers based on location, availability, and other factors

• Implement a dynamic pricing system to incentivize drivers to accept rides in high-demand areas

• Consider implementing a rating system for both riders and drivers to ensure quality service

• Utilize real-time data and analytics to optimize ride assignments and r
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Q1. Design BookMyShow
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Q1. What qualities do you see in a leader
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A leader should possess qualities such as communication skills, empathy, decisiveness, and the ability to inspire and motivate others.
• Communication skills - A leader should be able to effectively communicate with team members, stakeholders, and other leaders.

• Empathy - A good leader should be able to understand and relate to the emotions and experiences of others.

• Decisiveness - Leaders should be able to make tough decis...read more
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This was a live coding round where the problem statement was shared 15 minutes before the interview. The time duration was 2 hours.
The problem statement was a Driver allocation system. I had to write few APIs such as:
1) take input for source, destination, distance
2) allocate free driver to new booking
3) record driver's

The complete backend app had to be developed for this to make a working code. The database, language was completely free for choosing.
The program had to be developed on the system and code had to be shared on mail later.

Q1. Write a code in Go to find kth minumum element from a given list of numbers.
Ans. 
Code in Go to find kth minimum element from a given list of numbers.
• Sort the list of numbers in ascending order

• Return the kth element from the sorted list
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Q2. How do goroutines work internally?
Ans. 
Goroutines are lightweight threads that are managed by Go runtime.
• Goroutines are created using the 'go' keyword.

• They are multiplexed onto OS threads by Go runtime.

• They communicate using channels.

• They are scheduled cooperatively, not preemptively.

• They have a small stack size (2KB) compared to OS threads.

• They are used extensively in Go for concurrency and parallelism.
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Q1. Design a system for food delivery app like Swiggy. Then questions based on the design.
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Machine Coding Round

Low level design - ATM design

High level design - Uber

Q1. Director of engineering round
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Q2. Motivation to join the company
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Q3. Previous roles and responsibilities held
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