70+ Interview Questions and Answers

Virtual DOM is a lightweight copy of the real DOM, used for efficient updates.

• Real DOM updates are slow and expensive, while virtual DOM updates are fast and efficient.

• Virtual DOM is used in React to update the UI without reloading the entire page.

• Real DOM is the actual HTML document, while virtual DOM is a JavaScript object.

• Virtual DOM compares the previous and current states of the UI to determine the minimum number of changes needed.

• Real DOM updates require direct manipula...read more

Create dynamic buttons with JSON data, maintain active/inactive states, and show content on click

• Create buttons dynamically using JSON data

• Toggle between active and inactive states on click

• Display button content based on JSON data on click

var is function scoped, let and const are block scoped. var can be redeclared and reassigned, let can be reassigned but not redeclared, const cannot be reassigned or redeclared.

• var is hoisted to the top of the function, let and const are not

• var can be redeclared within the same scope, let and const cannot

• let and const have a temporal dead zone where they cannot be accessed before they are declared

• const cannot be reassigned, but the properties of a const object can be modified...read more

I have experience working with Agile methodology in my previous projects.

• I have worked in Scrum and Kanban frameworks.

• I have experience in conducting daily stand-up meetings, sprint planning, and retrospectives.

• I have worked in cross-functional teams and have experience in collaborating with product owners and stakeholders.

• I have used tools like Jira and Trello to manage tasks and track progress.

• In one of my previous projects, we used Agile methodology to develop a mobile app...read more

Answering questions related to sprint grooming, Scrum Master role, refresh tokens, Synthetic events, webpack, redux saga vs thunk, and hooks for Senior Software Engineer position.

• Sprint grooming involves prioritizing and estimating user stories for the upcoming sprint.

• Scrum Master facilitates the Scrum process and ensures the team follows the Agile principles.

• Refresh tokens are used to obtain new access tokens after the old ones expire.

• Synthetic events are artificially create...read more

I would choose a linked list as it allows for efficient insertion and deletion operations.

• Linked lists have constant time complexity for insertion and deletion operations

• Arrays have a linear time complexity for these operations

• Examples of linked list applications include implementing stacks and queues

• Arrays are better suited for random access and searching

SQL query to get 2nd highest salary

• Use ORDER BY and LIMIT to get the highest salary

• Use subquery to exclude the highest salary and get the 2nd highest

• Example: SELECT salary FROM employees ORDER BY salary DESC LIMIT 1,1

Optimization techniques in React include code splitting, lazy loading, and memoization.

• Code splitting: breaking down the code into smaller chunks to reduce load time.

• Lazy loading: loading components only when they are needed, reducing initial load time.

• Memoization: caching the results of expensive function calls to improve performance.

• Using shouldComponentUpdate to prevent unnecessary re-renders.

• Using React.PureComponent or implementing shouldComponentUpdate for functional co...read more

Technical interview questions on Kafka, Microservices, HashMap, Stack and Stock

• To connect Kafka to Spring Boot project, add Kafka dependencies in pom.xml and configure Kafka properties in application.properties

• Microservices communicate with each other through REST APIs or message brokers like Kafka or RabbitMQ

• HashMap internally uses an array of buckets to store key-value pairs. Collision is resolved by chaining or open addressing

• To reverse a stack, use an auxiliary stack to p...read more

Immutable class, remove duplicates from string using Java 8

• Create an immutable class to represent the string

• Use Java 8 streams to remove duplicates from the string

• Convert the string to a character array, use distinct() and collect() to remove duplicates

Hash map is a data structure that stores key-value pairs and uses a hash function to map keys to indices in an array.

• Hash function is used to convert the key into an index in the array

• Collisions occur when two keys map to the same index, which can be resolved using separate chaining or open addressing

• Load factor is the ratio of number of elements to the size of the array, and affects the performance of hash map

• Operations like insert, search and delete have an average time com...read more

Fallout mechanism between microservices refers to how failures in one microservice can impact other microservices.

• Fallout can occur due to cascading failures when one microservice depends on another.

• Implementing circuit breakers can help prevent fallout by isolating failures.

• Monitoring and alerting systems are crucial for detecting and responding to fallout.

• Using asynchronous communication can reduce the impact of fallout by decoupling services.

• Implementing retries and timeou...read more

I resolve conflicts by actively listening, understanding all perspectives, finding common ground, and proposing solutions.

• Actively listen to all parties involved

• Understand each perspective and the underlying reasons for conflict

• Find common ground and areas of agreement

• Propose solutions that address the concerns of all parties

Adding elements dynamically to an array in code

• Use push() method to add elements to an array in JavaScript

• In Python, use append() method to add elements to a list

• In Java, use ArrayList and add() method to dynamically add elements

I have worked on multiple projects involving containerization and developing APIs.

• Developed microservices using Docker containers for easy deployment and scalability

• Created RESTful APIs using Node.js and Express framework

• Integrated third-party APIs for data retrieval and processing

• Utilized Kubernetes for container orchestration and management

Technology is a boon for the future as it has the potential to solve complex problems and improve our lives.

• Technology can help us in various fields such as healthcare, education, and communication.

• It can improve the efficiency and accuracy of tasks, making them faster and more reliable.

• Artificial intelligence and machine learning can help us solve complex problems and make predictions.

• Technology can also help us connect with people from all over the world and share knowledge...read more

Use quicksort algorithm to sort array in one loop

• Use quicksort algorithm to partition array and sort elements

• Choose a pivot element and rearrange elements around pivot in one loop

• Repeat process for subarrays until entire array is sorted

Finding index of target element in a rotated sorted array.

• Use binary search to find the pivot point where the array is rotated.

• Determine which half of the array the target element lies in.

• Perform binary search on the appropriate half to find the target element index.

Find the longest substring in a given string with no repeated characters.

• Use a sliding window approach to keep track of the current substring.

• Use a hash set to keep track of the characters in the current substring.

• If a repeated character is found, move the start of the window to the next character after the first occurrence of the repeated character.

• Update the maximum length of the substring as the window slides through the string.

Hoisting is a JavaScript mechanism where variable and function declarations are moved to the top of their containing scope.

• Variable and function declarations are hoisted to the top of their scope during the compilation phase.

• Only the declarations are hoisted, not the initializations.

• Function declarations take precedence over variable declarations when hoisted.

Expected CTC should be based on industry standards, experience, skills, and location.

• Research industry standards for Software Engineer salaries

• Consider your experience level and skills when determining expected CTC

• Take into account the cost of living in the location of the job

• Negotiate based on the job responsibilities and market demand

To delete a node from a binary search tree (BST), we need to handle three cases: node has no children, node has one child, and node has two children.

• Start at the root and traverse the tree to find the node to be deleted.

• Handle the three cases: node has no children, node has one child, and node has two children.

• For a node with two children, find the inorder successor (smallest node in the right subtree) to replace the node to be deleted.

Sealed classes in Java restrict inheritance to a predefined set of subclasses.

• Sealed classes were introduced in Java 15 to restrict inheritance to a predefined set of subclasses.

• Subclasses of a sealed class must be declared in the same file as the sealed class.

• Sealed classes are declared using the 'sealed' modifier before the 'class' keyword.

• Example: sealed class Shape permits Circle, Square, Triangle;

Search for the minimum element in a rotated sorted array with duplicate elements.

• Use binary search to find the minimum element in the rotated sorted array.

• Handle the case where duplicate elements are present by adjusting the search conditions.

• Consider cases where the array is not rotated or contains only one element.

A hash table is the most suitable data structure for storing 1000+ records of a telephone directory.

• Hash tables provide constant time complexity for insertion, deletion, and retrieval operations.

• They use a key-value pair system, where the key is the phone number and the value is the corresponding contact information.

• Hash tables also have a low memory overhead compared to other data structures like arrays or linked lists.

• Example: Java's HashMap or Python's dict can be used to ...read more

HashSet is a collection that stores unique elements using a hash table.

• Uses hashing to store elements

• Does not allow duplicate elements

• Provides constant-time performance for basic operations like add, remove, contains

To design a tool like Google Looker, I would start by understanding the user's needs and requirements.

• Conduct user research to understand their needs and pain points

• Identify key features and functionalities required

• Create wireframes and prototypes to test and refine the design

• Collaborate with cross-functional teams to ensure seamless integration with existing systems

• Continuously gather feedback and iterate on the design

• Ensure scalability and security of the tool

To create a custom immutable class, use final keyword for class, private final fields, and no setter methods.

• Use the final keyword for the class to prevent inheritance

• Declare all fields as private and final to prevent modification

• Do not provide setter methods for the fields to maintain immutability

• Provide getter methods to access the fields

Swagger is for API design and documentation, Postman is for API testing and collaboration.

• Swagger is used for designing and documenting APIs

• Postman is used for testing and collaborating on APIs

• Swagger generates API documentation automatically

• Postman allows for easy API testing and debugging

• Both tools can be used together for a complete API workflow

The order of execution of a SQL code is: FROM, WHERE, GROUP BY, HAVING, SELECT, ORDER BY.

• FROM clause is executed first to retrieve data from tables

• WHERE clause filters the data based on specified conditions

• GROUP BY clause groups the data based on specified columns

• HAVING clause filters the grouped data

• SELECT clause selects the columns to display

• ORDER BY clause sorts the final result set

Remove duplicates from a 1D array of strings in place

• Iterate through the array and use a HashSet to keep track of unique elements

• Replace duplicates with null or an empty string to remove them in place

To troubleshoot a monitor issue, we can check the cables, update drivers, adjust display settings, and perform hardware tests. To resolve a BSOD issue, we can check for hardware or software conflicts, update drivers, run virus scans, and perform system restores.

• Check cables and connections

• Update drivers

• Adjust display settings

• Perform hardware tests

• Check for hardware or software conflicts

• Run virus scans

• Perform system restores

JavaScript coding tests typically involve solving programming challenges using JavaScript language.

• Solving algorithmic problems using JavaScript

• Implementing data structures and algorithms in JavaScript

• Writing functions to manipulate data or perform specific tasks

• Debugging and fixing code errors

• Implementing JavaScript frameworks or libraries in a project

Supply chain analytics involves using data and technology to optimize supply chain operations and improve decision-making.

• Supply chain analytics involves collecting and analyzing data related to supply chain processes, such as inventory levels, transportation costs, and supplier performance.

• It helps identify trends, patterns, and potential risks in the supply chain, allowing for better forecasting and planning.

• By leveraging advanced analytics tools like predictive modeling an...read more

Use SQL query to join tables on sales and survey

• Use JOIN keyword to combine tables based on a common column

• Specify the columns to select from each table

• Example: SELECT * FROM sales JOIN survey ON sales.id = survey.sales_id

My strategy to minimize cost would involve optimizing inventory levels, negotiating with suppliers for better pricing, and implementing efficient transportation routes.

• Optimizing inventory levels to reduce carrying costs

• Negotiating with suppliers for better pricing and terms

• Implementing efficient transportation routes to reduce shipping costs

Reverse the order of words in a given string.

• Split the string into an array of words using space as a delimiter.

• Reverse the array of words.

• Join the array of words back into a string using space as a separator.

Spring Actuator provides endpoints to monitor and manage microservices in a Spring Boot application.

• Add Spring Boot Actuator dependency in pom.xml

• Enable Actuator endpoints in application.properties or application.yml

• Access Actuator endpoints like /actuator/health, /actuator/info, etc.

• Customize Actuator endpoints using configuration properties

Yes, I am open for relocation.

• I am willing to relocate for the right opportunity

• I am open to exploring new places and cultures

• I understand that relocation may be necessary for career growth

A singleton class is a class that can only have one instance created throughout the application.

• Declare a private static instance variable of the class

• Create a private constructor to prevent external instantiation

• Provide a public static method to access the instance

Our current application architecture follows a microservices design pattern with a combination of front-end and back-end services.

• Utilizes Docker containers for easy deployment and scalability

• Uses RESTful APIs for communication between services

• Front-end built with React.js and back-end services in Node.js

• Data storage handled by MongoDB for flexibility and scalability

Graphs are used to represent relationships between objects. Shortest distance calculation is important in finding the most efficient path between two points.

• Graphs consist of nodes and edges that connect them.

• Shortest distance calculation can be done using algorithms like Dijkstra's algorithm or Bellman-Ford algorithm.

• Applications of graphs and shortest distance calculation include GPS navigation, network routing, and social network analysis.

String arrays are immutable because they cannot be changed once created.

• Strings in an array cannot be modified individually

• Any changes to a string array result in a new array being created

• Immutable arrays ensure data integrity and prevent unintended side effects

A palindromic substring is a string that reads the same forwards and backwards.

• Use dynamic programming to find the longest palindromic substring.

• Start by considering each character as the center of a potential palindrome.

• Expand outwards from each center to check for palindromes of odd and even lengths.

SQL normalization is the process of organizing a database to reduce redundancy and improve data integrity.

• Normalization involves breaking down a database into smaller, more manageable tables.

• It helps in reducing data redundancy by storing data in a structured manner.

• Normalization ensures data integrity by minimizing anomalies like insertion, update, and deletion anomalies.

• There are different normal forms like 1NF, 2NF, 3NF, BCNF, etc., each with specific rules to follow.

• For e...read more

Microservices architecture with containerization using Docker and Kubernetes

• Utilizes microservices architecture for scalability and flexibility

• Each microservice is containerized using Docker for easy deployment and management

• Orchestrated using Kubernetes for automated scaling and load balancing

Webflux is a reactive programming framework for building non-blocking, event-driven applications on the JVM.

• Webflux is part of the Spring Framework and provides support for reactive programming.

• It allows developers to build asynchronous, non-blocking applications that can handle a large number of concurrent connections.

• Webflux uses Project Reactor, a reactive library for building reactive applications.

• It supports both annotation-based and functional programming styles.

• Example...read more

Prepaid entry is a type of accounting entry where payment is made in advance for goods or services.

• Prepaid entry is recorded as an asset on the balance sheet until the goods or services are received.

• Once the goods or services are received, the prepaid entry is then recognized as an expense on the income statement.

• Examples of prepaid expenses include prepaid rent, insurance premiums, and prepaid advertising.

• Prepaid entry is important for accurate financial reporting and budget...read more

Bias and variance are two types of errors that can occur in a model.

• Bias refers to the error introduced by approximating a real-world problem, leading to underfitting.

• Variance refers to the error introduced by modeling the noise in the training data, leading to overfitting.

• Balancing bias and variance is crucial for creating a model that generalizes well to unseen data.

Hadoop is an open-source distributed processing framework that manages data processing and storage for big data applications.

• Hadoop consists of HDFS (Hadoop Distributed File System) for storage and MapReduce for processing.

• Hadoop uses a master-slave architecture with a single NameNode and multiple DataNodes.

• Data is stored in blocks across multiple DataNodes for fault tolerance and scalability.

• Hadoop ecosystem includes tools like Hive, Pig, Spark, and HBase for various data pr...read more

The requirements for the existing process involve understanding the current workflow, data sources, stakeholders, and desired outcomes.

• Analyze the current workflow and identify any bottlenecks or inefficiencies

• Identify all data sources being used in the process

• Engage with stakeholders to gather their input and requirements

• Document the desired outcomes and success criteria for the process

Course scheduling problem involves assigning courses to students and professors based on availability and preferences.

• The problem involves matching courses with students and professors based on their availability and preferences.

• Constraints such as class size, room availability, and time slots must be taken into account.

• Optimization techniques such as linear programming and genetic algorithms can be used to solve the problem.

• Examples include scheduling classes for a universit...read more

The golden rule of accounting is to record all transactions accurately and honestly.

• Always record transactions promptly and accurately

• Maintain clear and organized financial records

• Follow generally accepted accounting principles (GAAP)

• Ensure all financial statements are prepared accurately and honestly

• Regularly reconcile accounts to ensure accuracy

The three types of golden rules are the golden rule of accounting, the golden rule of ethics, and the golden rule of personal finance.

• Golden rule of accounting: Revenue should be recognized when it is earned, not when it is received. Expenses should be recognized when they are incurred, not when they are paid.

• Golden rule of ethics: Treat others as you would like to be treated. This principle guides ethical behavior and decision-making in various aspects of life.

• Golden rule of...read more

TCP is connection-oriented, reliable, and slower. UDP is connectionless, unreliable, and faster.

• TCP is connection-oriented, meaning a connection must be established before data can be transmitted.

• TCP is reliable as it ensures all data packets are received in order and without errors.

• TCP is slower than UDP due to the overhead of establishing and maintaining connections.

• UDP is connectionless, meaning data can be sent without establishing a connection first.

• UDP is unreliable as ...read more

The SAP T code for vendor master is XK01.

• XK01 is used to create a vendor master record in SAP.

• It allows users to enter all relevant information about a vendor, such as name, address, payment terms, etc.

• The vendor master record is essential for managing procurement and accounts payable processes in SAP.

• Other related T codes for vendor master include XK02 (change) and XK03 (display).

Implement a click counter in React

• Create a state variable to store the count

• Increment the count when a button is clicked

• Display the count in the UI

Event emitter in JavaScript allows objects to subscribe and listen for events.

• Event emitter is a design pattern where an object (the emitter) maintains a list of listeners and notifies them of events.

• Listeners can subscribe to specific events and execute a callback function when the event is emitted.

• Example: const emitter = new EventEmitter(); emitter.on('event', () => { console.log('Event emitted!'); }); emitter.emit('event');

• EventEmitter is a built-in module in Node.js that...read more

I have experience designing scalable and efficient software architectures for various projects.

• Utilize microservices architecture for scalability and flexibility

• Implement RESTful APIs for communication between components

• Use containerization with Docker for easy deployment and management

• Leverage cloud services like AWS or Azure for scalability and reliability

Scope in C++ refers to the region of the program where a variable can be accessed.

• Variables declared inside a function have local scope and can only be accessed within that function.

• Variables declared outside of any function have global scope and can be accessed throughout the program.

• Variables declared within a block have block scope and can only be accessed within that block.

• C++ also supports namespace scope, which allows variables to be grouped together under a common name...read more