Solulab inc Blockchain Developer Interview Questions and Answers

Q1. What is the difference between abstract class and an interface in Java?
Ans. 
Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.
• Abstract class can have constructors, member variables, and methods, while interface cannot.

• A class can implement multiple interfaces but can only extend one abstract class.

• Abstract classes are used to define a common behavior among subclasses, while interfaces are used to define a contract for classes to impl...read more
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Q2. An abstract class can have method implements and abstract method, while an interface only contains abstract method (before Java 8) . Abstract classes support single inheritance, whereas interfaces support ...read more
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Abstract classes can have both implemented and abstract methods, while interfaces can only have abstract methods. Abstract classes support single inheritance, interfaces support multiple inheritance.
• Abstract classes can have both implemented and abstract methods, providing more flexibility in design.

• Interfaces can only have abstract methods, promoting a more strict contract for implementing classes.

• Abstract classes sup...read more
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Q1. Number series in aptitude
Ans. 
Number series in aptitude involves identifying the pattern in a sequence of numbers and predicting the next number.
• Look for patterns such as arithmetic progression, geometric progression, or a combination of both.

• Check for alternate numbers, differences between consecutive numbers, or multiplication factors.

• Consider prime numbers, squares, cubes, or other mathematical operations applied to the series.

• Example: 2, 4, 6, ...read more
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Q2. Relation ships in berbal
Ans. 
Relationships in verbal communication are crucial for effective collaboration and understanding.
• Verbal communication involves both verbal and non-verbal cues

• Active listening is key to building strong relationships in verbal communication

• Clarity and conciseness in speech can enhance relationships

• Empathy and understanding of others' perspectives are important in verbal relationships
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Q1. Explain the four branches of oops
Ans. 
The four branches of OOP are encapsulation, inheritance, polymorphism, and abstraction.
• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Inheritance: Allowing a class to inherit properties and behavior from another class.

• Polymorphism: The ability for objects of different classes to respond to the same method call.

• Abstraction: Hiding the complex implementation details and showing only
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Q2. Explain about the structures in c
Ans. 
Structures in C are user-defined data types that allow grouping of variables of different data types under a single name.
• Structures are used to represent a record which consists of different data types.

• They are defined using the 'struct' keyword.

• Each variable in a structure is called a member.

• Structures can be nested within other structures.

• Example: struct employee { int emp_id; char emp_name[50]; float emp_salary; };

• E
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Q1. Can you introduce yourself?
Ans. 
Experienced Full Stack Developer with expertise in front-end and back-end technologies.
• Experienced in HTML, CSS, JavaScript for front-end development

• Proficient in Node.js, Express, MongoDB for back-end development

• Familiar with React, Angular for building interactive web applications
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Q2. What is graphQL?, What is REST API? and which is better graphQL or REST API?
Ans. 
GraphQL is a query language for APIs and a runtime for executing those queries. REST API is a set of rules for building web services. Both have their own advantages.
• GraphQL allows clients to request only the data they need, reducing over-fetching and under-fetching.

• REST API follows a more rigid structure and is easier to understand for beginners.

• GraphQL is more efficient for complex queries involving multiple resources...read more
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I was asked to discuss the system design of Google Meet, with a primary focus on video processing and WebRTC.

A graph question regarding LC 1334.

Q1. Can you provide an introduction and a summary of your past experiences, as well as your motivations for wanting to join this company?
Ans. 
Experienced Full Stack Developer with a passion for creating innovative solutions and a strong desire to contribute to a dynamic team.
• Over 5 years of experience in full stack development, working on various projects from concept to deployment.

• Proficient in front-end technologies such as HTML, CSS, JavaScript, and React.

• Skilled in back-end technologies including Node.js, Express, and MongoDB.

• Motivated by the opportunity...read more
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Questions on string and arrays both are moderate level questions on hacherrank type for 20 marks

Q1. Constructor chaining
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Q2. Hasmap and treemap
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Q1. Write a program for factorial of a number using for loop?
Ans. 
Program to calculate factorial of a number using for loop
• Initialize a variable to store the factorial result

• Use a for loop to iterate from 1 to the given number

• Multiply the current value with the factorial result in each iteration

• Return the factorial result
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Aptitude questions with some basic coding questions

They have given 3 coding questions and some pseudo codings

Q1. Tell about your self
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Q2. Some coding questions
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First round is online test of 3 virtual rounds consist of aptitude , and coding

Q1. Matrix multiplication
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Q2. Singly linked list
Ans. 
A singly linked list is a data structure where each element points to the next element in the list.
• Each node in the list contains data and a reference to the next node

• Traversal starts from the head node and follows the next pointers until the end

• Insertion and deletion can be done efficiently at the beginning or end of the list
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