100+ Interview Questions and Answers

Count the number of ways to reach target from source in a grid with 0s and 1s.

• Use dynamic programming to solve the problem efficiently.

• Traverse the grid using DFS or BFS to count the number of ways.

• Consider edge cases like when source and target are the same or when there is no path.

• Example: Given grid = [[0,0,0],[0,1,0],[0,0,0]], source = (0,0), target = (2,2), answer is 2.

• Example: Given grid = [[0,1],[0,0]], source = (0,0), target = (1,1), answer is 1.

Comparing 2 basketball game scenarios with different number of trials and baskets required to win

• Calculate the probability of winning in each game scenario using binomial distribution formula

• Compare the probabilities to determine which game scenario is preferable

• In game1, the probability of winning is p. In game2, the probability of winning is the sum of probabilities of making 2 or 3 baskets

• If p is high, game1 is preferable. If p is low, game2 is preferable

• For example, if p ...read more

Tech stack for designing a scalable Uber-like service.

• Use microservices architecture for scalability and fault tolerance.

• Choose a cloud provider with auto-scaling capabilities.

• Use a load balancer to distribute traffic across multiple instances.

• Use a NoSQL database for high availability and scalability.

• Use message queues for asynchronous communication between services.

• Use containerization for easy deployment and management.

• Use caching to improve performance.

• Use monitoring and ...read more

Design a service to aggregate multiple sources of data/documentation centrally.

• Identify sources of data/documentation

• Determine data aggregation method

• Design a centralized database to store aggregated data

• Develop a user-friendly interface to access the data

• Ensure data security and privacy

Visa is a global payments technology company that connects consumers, businesses, banks and governments in more than 200 countries and territories.

• Visa operates the world's largest retail electronic payments network.

• VisaNet, the company's global processing system, handles more than 65,000 transaction messages a second.

• Visa is constantly innovating to improve payment security and convenience, with initiatives such as Visa Checkout and tokenization.

• Visa is committed to financia...read more

Race condition is a situation where multiple threads/processes access and manipulate shared data simultaneously.

• It can be eliminated by using synchronization techniques like locks, semaphores, and mutexes.

• Another way is to use atomic operations that ensure the data is accessed and modified atomically.

• Using thread-safe data structures can also prevent race conditions.

• Example: Two threads trying to increment a shared variable simultaneously can cause a race condition.

• Example: U...read more

To scale a monolith architecture and improve response time, use horizontal scaling and implement caching.

• Implement horizontal scaling by adding more instances of the monolith application behind a load balancer

• Use a distributed cache to store frequently accessed data and reduce database queries

• Implement caching at different levels such as application-level caching, database query caching, and HTTP response caching

• Use a caching strategy based on the data access patterns and exp...read more

Need more context on the question to provide an answer.

• Please provide more information on the problem to be solved.

• Without context, it is difficult to provide a solution.

• Can you please provide more details on the problem statement?

Two trains starting from equator in opposite directions will not collide. Which train will have more wear and tear first?

• The train moving towards the east will have more wear and tear due to the rotation of the earth

• The train moving towards the west will have less wear and tear due to the rotation of the earth

• Air resistance will also affect the wear and tear of the trains

• The train moving towards the east will face more air resistance than the train moving towards the west

Merge two sorted arrays into the first array

• Start from the end of both arrays and compare elements

• Place the larger element at the end of the first array

• Continue this process until all elements are merged

Print the given Binary search tree in ascending order

• Traverse the left subtree recursively

• Print the root node

• Traverse the right subtree recursively

Chennai faces problems related to water scarcity, traffic congestion, and pollution.

• Water scarcity due to inadequate rainfall and poor management of water resources.

• Traffic congestion due to the increasing number of vehicles and poor road infrastructure.

• Pollution caused by industries, vehicular emissions, and improper waste disposal.

Implement Binary Search Tree using given array of strings.

• Sort the array in ascending order

• Find the middle element and make it the root of the tree

• Recursively create left and right subtrees using the left and right halves of the array

• Repeat until all elements are added to the tree

Ajax calls allow for asynchronous communication between client and server without reloading the page.

• Ajax stands for Asynchronous JavaScript and XML

• Uses XMLHttpRequest object to send and receive data

• Allows for partial page updates without reloading the entire page

• Can handle data in various formats such as JSON, XML, HTML, and plain text

• Example: $.ajax({url: 'example.com', success: function(data){console.log(data)}});

Creating immutable in Java

• Use final keyword to make variables immutable

• Use private constructor to prevent object modification

• Use defensive copying to prevent modification of mutable objects

• Use enum to create immutable objects

• Use String class to create immutable strings

Design a cache class with get(), put(), and initialization methods.

• Define a class with a data structure to store key-value pairs.

• Implement a get() method to retrieve a value from the cache based on a given key.

• Implement a put() method to add or update a key-value pair in the cache.

• Implement an initialization method to set the initial capacity and eviction policy of the cache.

• Consider using a hash map or a linked list to store the key-value pairs efficiently.

• Handle cache size ...read more

Immutable is used in Java to create objects whose state cannot be changed after creation.

• Immutable objects are thread-safe and can be shared without the risk of data corruption.

• Examples of immutable classes in Java include String, Integer, and LocalDate.

• Immutable objects can be created using the final keyword, constructor initialization, and static factory methods.

React lifecycle functions are methods that are automatically called at specific points in a component's life cycle.

• Mounting: constructor, render, componentDidMount

• Updating: render, componentDidUpdate

• Unmounting: componentWillUnmount

Visa is a payment processing company that facilitates electronic funds transfers globally.

• Visa operates a network that connects financial institutions, merchants, and consumers worldwide.

• The company provides payment products and services, including credit and debit cards, prepaid cards, and digital wallets.

• Visa's payment processing system involves authorization, clearing, and settlement of transactions.

• To design a scalable file access system like Dropbox or Google Drive, one ...read more

My project is a mobile app that helps users track their daily exercise and nutrition.

• Ensure the app is user-friendly and intuitive

• Implement a secure login and authentication system

• Integrate with fitness trackers and nutrition databases

• Perform thorough testing and bug fixing

• Consider scalability and performance optimization

• Implement a monetization strategy for commercial use

BUS topology is preferred for small networks while ring topology is preferred for larger networks.

• BUS topology is easier to install and maintain than ring topology.

• Ring topology is more fault-tolerant than BUS topology.

• BUS topology is suitable for small networks with few devices while ring topology is suitable for larger networks with many devices.

• Ring topology is more expensive than BUS topology.

• Examples of BUS topology include Ethernet and USB while examples of ring topolog...read more

OOPS concepts include abstraction, inheritance, polymorphism, and encapsulation.

• Abstraction: Hiding implementation details and showing only necessary information.

• Inheritance: Creating new classes from existing ones, inheriting properties and methods.

• Polymorphism: Using a single method to perform different actions based on the object type.

• Encapsulation: Binding data and methods together, protecting data from outside interference.

The time taken by the kth person to collect n number of tickets can be calculated using a formula.

• Use the formula: time = (n - 1) * k

• Subtract 1 from n because the first person doesn't need to wait for anyone

• Multiply the result by k to get the time taken by the kth person

• Example: If n = 5 and k = 3, the time taken by the 3rd person would be (5 - 1) * 3 = 12

A credit/debit card typically contains the cardholder's name, card number, expiration date, and security code.

• Cardholder's name

• Card number

• Expiration date

• Security code/CVV

• Card issuer logo

• Magnetic stripe

• Chip

• Contactless payment symbol

Observer pattern is a design pattern in which an object maintains a list of its dependents and notifies them automatically of any state changes.

• Also known as publish-subscribe pattern

• Used in event-driven systems

• Allows loose coupling between objects

• Example: A weather station broadcasts weather updates to multiple displays

• Example: A stock market ticker notifies multiple investors of stock price changes

Unit testing involves testing individual units of code to ensure they function as expected.

• Identify the individual units of code to be tested

• Create test cases for each unit, covering all possible scenarios

• Execute the tests and analyze the results

• Refactor the code as necessary based on the test results

I primarily use SSH (Secure Shell) to connect servers.

• SSH (Secure Shell) is a widely used application for securely connecting to servers

• Other applications like PuTTY, OpenSSH, and WinSCP can also be used for server connections

Testing principles ensure software quality, while design principles guide software development.

• Testing principles include unit testing, integration testing, and acceptance testing.

• Design principles include SOLID, DRY, and KISS.

• Testing principles ensure that software meets requirements and is free of defects.

• Design principles guide software development to be modular, maintainable, and scalable.

REST is lightweight and uses HTTP while SOAP is XML-based and has more features.

• REST uses HTTP methods like GET, POST, PUT, DELETE while SOAP uses XML messaging.

• REST is stateless while SOAP can maintain state.

• REST is faster and easier to use while SOAP is more secure and reliable.

• REST is used for web services while SOAP is used for enterprise-level services.

• Example of REST: Twitter API. Example of SOAP: Amazon Web Services.

A multi-layered approach is needed to prevent DoS and network attacks.

• Implement firewalls and intrusion detection systems

• Use load balancers to distribute traffic

• Regularly update software and security patches

• Limit access to sensitive data and systems

• Educate employees on safe browsing habits and phishing scams

Custom data structure for array of strings

• Use a trie data structure to efficiently store and search for strings

• Implement methods for adding, removing, and searching for strings in the trie

• Consider optimizing the trie for memory usage and performance

Understanding internal workings of DB structures and indices is crucial for optimizing database performance.

• DB structures refer to how data is organized within a database, such as tables, columns, and relationships.

• Indices are data structures that improve the speed of data retrieval operations by providing quick access to specific data values.

• Understanding how indices work can help in optimizing query performance by reducing the number of rows that need to be scanned.

• Common t...read more

Padding is the space inside the border of an element, while margin is the space outside the border.

• Padding is used to create space between the content and the border of an element.

• Margin is used to create space between the border of an element and other elements.

• Padding affects the size of the content area, while margin affects the positioning of the element.

• Example: padding: 10px will create 10 pixels of space inside the border of an element.

• Example: margin: 20px will create...read more

Data mining on VISA data can provide insights on consumer spending patterns and fraud detection.

• Identifying consumer spending habits and preferences

• Detecting fraudulent transactions and patterns

• Analyzing purchasing trends and market behavior

• Predicting customer churn and loyalty

• Optimizing marketing campaigns and personalized offers

Immutable in Java refers to objects whose state cannot be changed after creation.

• String, Integer, and other wrapper classes are immutable in Java.

• Immutable objects are thread-safe and can be shared without synchronization.

• To create an immutable class, make all fields final and private, and don't provide setters.

• Examples of immutable classes in Java include LocalDate, LocalTime, and LocalDateTime.

Dependency injection is a design pattern that allows objects to receive dependencies rather than creating them internally.

• It helps to decouple the code and makes it more testable and maintainable.

• It allows for easier swapping of dependencies without changing the code.

• There are three types of dependency injection: constructor injection, setter injection, and interface injection.

• Example: Instead of creating a database connection object inside a class, the object is passed as a ...read more

These are three different programming problems that require different approaches to solve.

• N-Queens: placing N queens on an NxN chessboard so that no two queens threaten each other

• Snake and Ladder Problem: finding the minimum number of dice rolls to reach the end of a board with snakes and ladders

• Second Most Repeated Word in a Sequence: finding the second most frequently occurring word in a given sequence of words

Using pandas in Python to perform tasks for a Software Engineer interview question

• Import pandas library

• Read data from a CSV file using pandas

• Perform data manipulation and analysis using pandas functions

• Write the processed data back to a new CSV file

To modify a Gmail notifier, you can customize its appearance, add additional features, or integrate it with other applications.

• Customize the notifier's appearance by changing its color, font, or notification sound.

• Add additional features such as the ability to mark emails as read or reply directly from the notifier.

• Integrate the notifier with other applications like a task manager or calendar to display reminders or deadlines.

• Implement filters to only receive notifications fo...read more

Regression testing is the process of testing changes made to a software application to ensure that existing functionality still works.

• It is performed after making changes to the software

• It ensures that existing functionality is not affected by the changes

• It helps to catch any defects or bugs that may have been introduced

• It can be automated using testing tools

• Examples include retesting after bug fixes, testing after new features are added

GET and POST are HTTP methods used for sending data to a server.

• GET is used to retrieve data from a server

• POST is used to submit data to a server

• GET requests can be cached and bookmarked

• POST requests are not cached and cannot be bookmarked

• GET requests have length restrictions

• POST requests have no length restrictions

• GET requests are less secure than POST requests

Autocomplete in IDEs helps developers write code faster by suggesting code snippets and completing code as they type.

• Autocomplete should suggest code snippets based on the context of the code being written

• Autocomplete should prioritize suggestions based on frequency of use

• Autocomplete should also suggest variable and function names

• Autocomplete should be customizable to allow for user-defined snippets and suggestions

• Examples of IDEs with autocomplete include Visual Studio Code...read more

CORS stands for Cross-Origin Resource Sharing. It is a security feature implemented in web browsers to restrict access to resources from different origins.

• CORS allows web servers to specify which origins are allowed to access its resources

• It is implemented using HTTP headers

• CORS prevents malicious websites from accessing sensitive data from other websites

• Examples of resources that may be restricted by CORS include cookies, scripts, and APIs

Supporting application for SSO enablement involves configuring authentication settings, integrating with identity providers, and testing functionality.

• Configure authentication settings within the application to enable SSO

• Integrate the application with identity providers such as Okta, Azure AD, or PingFederate

• Test the SSO functionality to ensure seamless user experience

• Provide documentation and training for users on how to use SSO with the application

Enable SSO for SaaS applications by integrating with identity providers and configuring authentication protocols.

• Integrate with identity providers such as Okta, Azure AD, or Google Workspace

• Configure authentication protocols like SAML, OAuth, or OpenID Connect

• Implement single sign-on functionality in the application code

• Ensure secure communication between the application and the identity provider

Yes, I have experience in taking care of the Authorization part in various projects.

• Implemented role-based access control (RBAC) to manage user permissions

• Configured and managed authentication protocols such as OAuth and SAML

• Worked on setting up access control lists (ACLs) for network security

• Experience with managing user roles and permissions in Active Directory

• Utilized single sign-on (SSO) solutions for seamless user authentication

SDLC refers to the process of software development. Different models include Waterfall, Agile, Spiral, and V-Model.

• Waterfall model follows a linear sequential approach with distinct phases like planning, design, development, testing, and maintenance.

• Agile model emphasizes on iterative and incremental development with continuous feedback and collaboration between cross-functional teams.

• Spiral model combines the elements of both Waterfall and Agile models with risk analysis and...read more

Replace each element with the greatest element on its right side in the array

• Loop through the array from right to left

• Keep track of the maximum element seen so far

• Replace the current element with the maximum element seen so far

• Return the modified array

Singleton is a design pattern that restricts the instantiation of a class to a single object.

• Singleton ensures that only one instance of a class exists in the entire application.

• It provides a global point of access to the instance.

• Commonly used in scenarios where a single instance needs to coordinate actions across the system.

• Example: Database connection manager, logger, configuration manager.

I am expecting a competitive salary based on my experience and the responsibilities of the role.

• I am open to negotiation based on the company's budget and benefits package.

• I have researched the average salary range for this position in the industry and location.

• I am confident in my skills and experience and believe I can bring value to the company.

• I am looking for a fair and reasonable compensation package that reflects my contributions to the company's success.

I will go into great depth to understand the system design, including analyzing all components and interactions.

• I will thoroughly review the system architecture, including all components and their interactions.

• I will analyze the data flow within the system to understand how information is processed and shared.

• I will consider scalability and performance requirements to ensure the system can handle future growth.

• I will collaborate with stakeholders and technical experts to gain...read more

JCube is a Java library for creating and manipulating Rubik's Cube puzzles.

• JCube provides classes for representing Rubik's Cube puzzles and algorithms for solving them.

• It supports various cube sizes and can generate random scrambles.

• JCube can be used in Java applications or as a standalone command-line tool.

• It is open source and available on GitHub.

I have experience working with both connected and disconnected applications.

• I have experience developing applications that can function both online and offline.

• I have worked on projects where data synchronization is crucial for seamless user experience.

• Examples include mobile apps that can work offline and sync data when connected to the internet.

Given an array of integers, find two numbers that add up to a given target value.

• Use a hash map to store the difference between the target value and each element in the array.

• Iterate through the array and check if the current element exists in the hash map.

• If it does, return the indices of the two numbers.

• If no solution is found, return an empty array.

I handle change management by implementing structured processes, communication, and stakeholder involvement.

• Implementing a change management process to track and document changes

• Communicating changes effectively to all stakeholders

• Involving key stakeholders in decision-making and planning

• Ensuring proper testing and validation of changes before implementation

RTO stands for Recovery Time Objective in disaster recovery, representing the targeted duration of time within which a business process must be restored after a disaster.

• RTO is a crucial metric in disaster recovery planning, indicating the maximum acceptable downtime for a system or process.

• It helps organizations determine the resources and strategies needed to recover from a disaster within a specific timeframe.

• For example, if a company sets an RTO of 4 hours for its critica...read more

A class in Java is a blueprint or template for creating objects that encapsulate data and behavior.

• A class can contain fields, methods, constructors, and nested classes

• Objects are instances of a class

• Inheritance allows a class to inherit properties and methods from another class

• Polymorphism allows objects of different classes to be treated as if they are of the same class

• Example: class Car { String make; int year; void start() { ... } }

• Example: Car myCar = new Car(); myCar.ma...read more

Software engineering principles are the best practices and guidelines for developing high-quality software.

• Software should be designed with modularity and scalability in mind.

• Code should be well-documented and easy to read.

• Testing and debugging should be an integral part of the development process.

• Version control should be used to manage code changes.

• Security and privacy should be considered throughout the development lifecycle.

A circular linked list is a data structure where the last node points back to the first node, forming a loop.

• Create a Node class with data and next pointer

• Initialize the head node and set its next pointer to itself

• To add a node, create a new node and set its next pointer to the head node's next pointer, then update the head node's next pointer to the new node

• To traverse the circular linked list, start from the head node and continue until reaching the head node again

Spring Boot API endpoint is a URL that exposes the functionality of a web service.

• API endpoints are the entry points for the client to access the server's resources.

• Spring Boot provides a simple and easy way to create RESTful APIs.

• Endpoints can be secured using Spring Security.

• Endpoints can be documented using Swagger or Spring REST Docs.

• Examples: /users, /products, /orders

A Singleton class is a class that can only have one instance at a time.

• It restricts the instantiation of a class to a single object.

• It provides a global point of access to that instance.

• It is often used in situations where a single object is required to coordinate actions across a system.

• Example: Database connection manager, Configuration manager, Logger manager.

Code a basic linked list

• Create a Node class with data and next pointer

• Create a LinkedList class with head pointer

• Implement methods to add, delete, and search nodes in the linked list

A binary tree is a data structure in which each node has at most two children.

• Start with a root node

• Each node has a left and right child

• Nodes can be added or removed

• Traversal can be done in-order, pre-order, or post-order

Reconciling GL and subledger involves identifying and resolving discrepancies between the two accounts.

• Compare transactions in GL and subledger to identify discrepancies

• Investigate any differences in balances or transactions

• Adjust entries in GL or subledger to reconcile the accounts

• Ensure proper documentation of reconciliation process

• Communicate with relevant stakeholders to resolve discrepancies

Separate even and odd numbers in an array

• Iterate through the array and check if each number is even or odd

• Create two separate arrays for even and odd numbers

• Add the even numbers to the even array and odd numbers to the odd array

• Return both arrays as the result

A timer can be implemented using a combination of system time and a loop that checks for elapsed time.

• Get the current system time at the start of the timer

• Enter a loop that continuously checks the difference between the current system time and the start time

• When the desired time has elapsed, perform the desired action or trigger an event

useEffect is a hook in React that allows you to perform side effects in functional components.

• useEffect is used to handle side effects in React components.

• It takes two arguments: a function and an optional array of dependencies.

• The function inside useEffect is executed after the component renders.

• The optional array of dependencies determines when the effect should run.

• If the array of dependencies is empty, the effect runs only once after the initial render.

• If the array of dep...read more

Yes, I have worked in an agile environment before.

• I have experience working in Scrum and Kanban methodologies

• I have participated in daily stand-up meetings, sprint planning, and retrospectives

• I have collaborated closely with developers, product owners, and other team members to deliver high-quality software

Yes, I am experienced in vulnerability management.

• I have experience in identifying, prioritizing, and mitigating vulnerabilities in systems and networks.

• I am proficient in using vulnerability scanning tools such as Nessus, Qualys, and OpenVAS.

• I have implemented patch management processes to address vulnerabilities in a timely manner.

• I have conducted vulnerability assessments and penetration testing to identify weaknesses in systems.

• I have worked on creating and implementing s...read more

Various types of testing are used in projects to ensure quality and functionality.

• Unit testing: Testing individual components or units of code.

• Integration testing: Testing the interaction between different components or modules.

• System testing: Testing the entire system to ensure it meets the requirements.

• Performance testing: Testing the system's performance under different loads.

• Security testing: Testing the system's vulnerability to security threats.

• User acceptance testing: ...read more