70+ Rail Infrastructure Development Company Interview Questions and Answers

Microservices are implemented using RESTful APIs and message brokers for asynchronous communication.

• RESTful APIs are used for synchronous communication between microservices.

• Message brokers like Kafka or RabbitMQ are used for asynchronous communication.

• Microservices communicate with each other using HTTP requests and responses.

• Each microservice has its own database and communicates with other microservices through APIs.

• Microservices are loosely coupled and can be developed an...read more

I follow the MVC design pattern as it separates concerns and promotes code reusability.

• MVC separates the application into Model, View, and Controller components.

• Model represents the data and business logic.

• View represents the user interface.

• Controller handles user input and updates the model and view accordingly.

• MVC promotes code reusability and maintainability.

• Example: Ruby on Rails framework follows MVC pattern.

Design a Java-like Garbage Collector with minimal configurations.

• Choose a garbage collection algorithm (e.g. mark-and-sweep, copying, generational)

• Determine the heap size and divide it into regions (e.g. young, old, permanent)

• Implement a root set to keep track of live objects

• Set thresholds for garbage collection (e.g. occupancy, time)

• Implement the garbage collection algorithm and test for memory leaks

Memoization is a technique used in programming to store the results of expensive function calls and return the cached result when the same inputs occur again.

• Memoization helps improve the performance of a function by caching its results.

• It is commonly used in dynamic programming to optimize recursive algorithms.

• Example: Memoizing a Fibonacci function to avoid redundant calculations.

An unique id for a massive parallel system can be generated using a combination of timestamp, machine id and a random number.

• Use a timestamp to ensure uniqueness

• Include a machine id to avoid collisions in a distributed system

• Add a random number to further increase uniqueness

• Consider using a UUID (Universally Unique Identifier) for simplicity

• Ensure the id generation algorithm is thread-safe

A Promise is an object representing the eventual completion or failure of an asynchronous operation.

• A Promise is used to handle asynchronous operations in JavaScript.

• It represents a value that may be available now, or in the future.

• A polyfill for Promise can be implemented using the setTimeout function to simulate asynchronous behavior.

Instagram uses a notification system to alert users when they are tagged and displays reels on the profile page based on user preferences and algorithms.

• Instagram uses a push notification system to alert users when they are tagged in a post or story.

• Reels are displayed on the profile page based on user engagement, preferences, and algorithms.

• The Explore page also suggests reels to users based on their interests and interactions on the platform.

OLA application uses GPS to track cabs on map and assign them to customers based on location and availability.

• OLA application uses GPS technology to track the location of cabs in real-time.

• Customers input their location and destination in the app to request a cab.

• The app matches the customer with the nearest available cab and assigns it to them.

• Customers can track the cab's movement on the map in real-time as it approaches their location.

Design HLD and LLD of Zomato

• High-Level Design (HLD) should include the overall architecture of the system, including components and their interactions

• Low-Level Design (LLD) should include detailed design of each component, including data structures, algorithms, and interfaces

• HLD should consider scalability, availability, and fault tolerance

• LLD should consider performance, security, and maintainability

• Example components of Zomato system: user interface, search engine, recommen...read more

Hyperparameters of XGBoost, Random Forest, and SVM can be tuned using techniques like grid search, random search, and Bayesian optimization.

• For XGBoost, important hyperparameters to tune include learning rate, maximum depth, and number of estimators.

• For Random Forest, important hyperparameters to tune include number of trees, maximum depth, and minimum samples split.

• For SVM, important hyperparameters to tune include kernel type, regularization parameter, and gamma value.

• Grid ...read more

Design and code a scheduler for allocating meeting rooms based on input of room counts and timestamps.

• Create a table with columns for room number, start time, and end time

• Use SQL queries to check for available slots and allocate rooms

• Consider edge cases such as overlapping meetings and room availability

• Use a loop to continuously check for available slots and allocate rooms

• Implement error handling for invalid input

Remove leaf nodes of a tree

• Traverse the tree in postorder fashion

• For each node, check if it is a leaf node (both children are null)

• If it is a leaf node, remove it by setting its parent's reference to null

Hyperparameters are settings that control the behavior of machine learning algorithms.

• Hyperparameters are set before training the model.

• They control the learning process and affect the model's performance.

• Examples include learning rate, regularization strength, and number of hidden layers.

• Optimizing hyperparameters is important for achieving better model accuracy.

Zomato is a food delivery and restaurant discovery platform that connects users with local restaurants.

• Zomato uses a microservices architecture to handle its various functionalities.

• The system is designed to handle a large number of concurrent users and requests.

• Zomato uses a combination of relational and NoSQL databases to store data.

• The platform uses machine learning algorithms to provide personalized recommendations to users.

• Zomato also integrates with various third-party ...read more

Design a parking lot system

• Consider the size and layout of the parking lot

• Include features like ticketing system, payment options, and security measures

• Implement a system to track available parking spaces and manage vehicle entry/exit

A parking lot system that manages parking spots and vehicles.

• Create a class for parking lot with attributes like total number of spots, available spots, etc.

• Create a class for vehicle with attributes like license plate number, type, etc.

• Implement methods for parking a vehicle, removing a vehicle, and checking availability of spots.

• Use data structures like arrays and maps to store and retrieve information.

• Consider implementing a payment system for parking fees.

Steps to fit a time series model

• Identify the time series pattern

• Choose a suitable model

• Split data into training and testing sets

• Fit the model to the training data

• Evaluate model performance on testing data

• Refine the model if necessary

• Forecast future values using the model

Detect if there is a loop in a graph.

• Use Depth First Search (DFS) to traverse the graph.

• If a node is visited twice during DFS, then there is a loop.

• Maintain a visited set to keep track of visited nodes.

• If a node is already in the visited set, then there is a loop.

Ridge and LASSO are regularization techniques used in linear regression to prevent overfitting.

• Ridge adds a penalty term to the sum of squared errors, which shrinks the coefficients towards zero but doesn't set them exactly to zero.

• LASSO adds a penalty term to the absolute value of the coefficients, which can set some of them exactly to zero.

• The geometric interpretation of Ridge is that it adds a constraint to the size of the coefficients, which shrinks them towards the origi...read more

The popular temple in my village is the Sri Ranganathaswamy Temple.

• Located in the heart of the village

• Dedicated to Lord Ranganatha

• Annual festivals and rituals attract devotees from neighboring villages

Expected compensation for software engineers varies based on experience, location, and company size.

• Compensation can range from $60,000 to $200,000+ per year depending on factors such as experience level, location, and company.

• Additional benefits like stock options, bonuses, and perks can also impact overall compensation.

• Research industry standards and use resources like Glassdoor or Payscale to determine a fair salary range.

• Negotiate based on your skills, experience, and the...read more

RNN and CNN are neural network architectures used for different types of data.

• RNN is used for sequential data like time series, text, speech, etc.

• CNN is used for grid-like data like images, videos, etc.

• RNN has feedback connections while CNN has convolutional layers.

• RNN can handle variable length input while CNN requires fixed size input.

• Both can be used for classification, regression, and generation tasks.

Find the smallest palindrome and lowest common ancestor in a given tree

• To find the smallest palindrome, iterate through the string and check if it is a palindrome. Return the smallest one found.

• To find the lowest common ancestor in a tree, use a recursive approach to traverse the tree and find the common ancestor of two nodes.

My strength lies in my problem-solving skills and ability to learn quickly.

• Strong problem-solving skills

• Quick learner

• Adaptability to new technologies

• Ability to work well under pressure

Support from my team, access to resources, clear communication

• Support from my team helps me stay motivated and overcome challenges

• Access to resources such as training materials and tools enables me to perform my job effectively

• Clear communication ensures that I understand project requirements and expectations

I am proficient in 5 programming languages including Java, Python, C++, JavaScript, and SQL.

• Java

• Python

• C++

• JavaScript

• SQL

Effective communication with geographically dispersed teams requires clear communication channels, cultural sensitivity, and regular check-ins.

• Establish clear communication channels such as video conferencing, instant messaging, and email

• Be sensitive to cultural differences and adapt communication style accordingly

• Schedule regular check-ins to ensure everyone is on the same page and address any concerns or issues

• Encourage open communication and active listening to foster coll...read more

DSA questions on array and binary tree manipulation

• For printing pairs with target sum, use a hash table to store frequency of elements and check if complement exists

• For converting array to BST, use binary search to find the middle element and recursively build left and right subtrees

• For top view of binary tree, use a queue to traverse the tree level by level and store horizontal distance of nodes

• For minimum number of jumps, use dynamic programming to find minimum jumps requir...read more

SCC stands for Source Code Control. It is a system used to manage and track changes to source code files.

• SCC helps developers collaborate on code by providing version control and tracking changes.

• Popular SCC tools include Git, SVN, and Mercurial.

• SCC allows developers to revert to previous versions of code, track changes made by team members, and merge code changes seamlessly.

• SCC helps in maintaining code integrity and ensuring that the latest version of code is always availab...read more

The new code of wages is a legislation that aims to simplify and standardize wage-related regulations in India.

• The code replaces four existing laws related to wages and payment of bonus.

• It introduces a universal definition of wages and sets a minimum wage for all workers.

• The code also mandates equal pay for men and women for the same work.

• It is expected to reduce compliance costs for employers and improve transparency in wage payments.

• However, some experts have raised concern...read more

Intermediate refers to a level of proficiency or knowledge that falls between beginner and advanced.

• Intermediate level typically involves a deeper understanding of concepts and the ability to apply them in practical scenarios.

• Individuals at an intermediate level may have some experience in the field but still have room for growth and learning.

• Examples of intermediate skills include proficiency in a programming language, familiarity with common algorithms, and ability to work ...read more

The retail company was successful in expanding its market share and increasing revenue through strategic partnerships and innovative marketing campaigns.

• The retail company focused on customer experience and satisfaction to drive repeat business.

• Implemented data-driven decision making to optimize inventory management and pricing strategies.

• Utilized social media and digital marketing to reach a wider audience and increase brand awareness.

• Established partnerships with popular in...read more

Technical features desinetions to better understand

• Technical features refer to the specific functionalities and capabilities of a digital marketing tool or platform

• They help marketers understand how the tool can be used to achieve their marketing goals

• Examples of technical features include analytics tracking, A/B testing, email automation, and social media scheduling

• Understanding these features is crucial for effective digital marketing strategy and campaign execution

AOP stands for Annual Operating Plan. It is a detailed plan of an organization's revenue and expenses for the upcoming year.

• AOP is prepared by analyzing past performance, market trends, and future goals.

• It includes revenue projections, expense budgets, and capital expenditure plans.

• AOP is usually prepared by the finance department in collaboration with other departments.

• It is an important tool for financial planning and helps in setting targets and monitoring progress.

• Example...read more

Pivot table for summarizing data, vlookup for finding values in a table, hlookup for horizontal lookup, xlookup for advanced lookup.

• Pivot table is used to summarize and analyze large datasets.

• VLOOKUP is used to find a value in a table by row.

• HLOOKUP is used to find a value in a table by column.

• XLOOKUP is a more advanced version of VLOOKUP and HLOOKUP, allowing for more flexibility in searching for data.

• Example: Use pivot table to summarize sales data, VLOOKUP to find a custom...read more

Market basket analysis is a technique used to understand the relationships between products purchased together by customers.

• It involves analyzing transaction data to identify patterns and associations between products frequently bought together.

• The goal is to uncover insights that can be used for product placement, cross-selling, and targeted marketing.

• Commonly used in retail and e-commerce to optimize product recommendations and promotions.

• Example: If customers who buy diape...read more

Standard ADSO is for persistent storage and reporting, while write optimized DSO is for temporary storage. Keys in ADSO are used for data modeling and performance optimization.

• Standard ADSO is used for persistent storage and reporting, while write optimized DSO is used for temporary storage before loading data to a standard ADSO.

• Write optimized DSO does not store data persistently, making it suitable for temporary data storage during data loads.

• Keys in ADSO are defined to uni...read more

The important role of a cashier is to handle financial transactions accurately and efficiently.

• Accurately processing cash, credit, and debit transactions

• Providing excellent customer service

• Maintaining a clean and organized cash register area

• Balancing cash drawer at the end of each shift

• Resolving customer complaints or issues

• Following company policies and procedures

• Upselling products or services when appropriate

Designing a search engine system involves creating algorithms for indexing, ranking, and retrieving relevant information.

• Consider using inverted index for efficient searching

• Implement ranking algorithms like PageRank or TF-IDF

• Utilize web crawlers to gather and index web pages

• Include features like autocomplete and spell correction for user-friendly experience

Catalog Analyst role involves managing product data, ensuring accuracy and consistency in catalogs.

• Responsible for creating, updating, and maintaining product catalogs

• Ensuring accuracy and consistency of product data

• Analyzing catalog performance and making recommendations for improvements

• Collaborating with cross-functional teams such as marketing, sales, and product development

• Knowledge of data management systems and tools like Excel, SQL, or ERP systems

Implement a React stopwatch with start, stop, resume, and pause functionalities.

• Use state to track the elapsed time

• Create functions for start, stop, resume, and pause actions

• Use setInterval for updating the timer every second

• Display the timer in the UI

Memory leaks in JavaScript happen when unused objects are not properly released from memory.

• Memory leaks can occur when variables are not properly dereferenced, preventing garbage collection.

• Closures can also lead to memory leaks if they hold references to large objects.

• Event listeners can cause memory leaks if not removed properly after use.

• Using setInterval without clearing it can lead to memory leaks.

• Circular references can also cause memory leaks in JavaScript.

The Ten foot rule is a customer service principle where employees are expected to acknowledge and greet customers within ten feet of them.

• Acknowledge and greet customers within ten feet of you

• Show a friendly and welcoming attitude towards customers

• Offer assistance or answer any questions they may have

• Make customers feel valued and attended to

• Examples: Saying 'Hello, how can I help you today?' to a customer approaching your area

Complete employee life cycle refers to the stages an employee goes through during their employment with a company.

• Recruitment and onboarding

• Performance management

• Career development and training

• Compensation and benefits

• Offboarding or separation

• Examples: hiring, orientation, performance reviews, promotions, retirement, termination

Create a UI component to display matched results in a dropdown

• Use HTML, CSS, and JavaScript to create the dropdown component

• Implement a search functionality to filter and display matched results

• Use event listeners to handle user interactions like selecting a result

Increasing sales can be achieved by implementing effective marketing strategies, improving customer service, offering promotions, and expanding the product line.

• Implement targeted marketing campaigns to reach potential customers

• Provide excellent customer service to retain existing customers and attract new ones

• Offer promotions such as discounts, buy-one-get-one-free deals, or loyalty programs to incentivize purchases

• Expand the product line to cater to a wider range of custome...read more

LC mediums refer to LeetCode mediums, which are medium difficulty coding problems on the LeetCode platform.

• LC mediums are coding problems with medium difficulty level on LeetCode platform.

• Solving 3 LC mediums in 30 minutes requires good problem-solving skills and efficient coding techniques.

• Examples of LC mediums include 'Longest Substring Without Repeating Characters' and 'Container With Most Water'.

Reading values from URL using map vs for loop in JavaScript

• Use the window.location.search property to get the query string from the URL

• Map can be used to transform each value in the query string array

• For loop can be used to iterate through each value in the query string array

Mapping a process involves identifying its steps and creating a visual representation of the flow.

• Identify the process to be mapped

• List the steps involved in the process

• Create a flowchart or diagram to represent the process

• Include decision points and potential outcomes

• Review and refine the process map as needed

Various ways to ingest data in BigQuery include batch loading, streaming, and using third-party tools.

• Batch loading: Uploading data in bulk using tools like Cloud Storage or Data Transfer Service.

• Streaming: Sending data in real-time using APIs like Dataflow or Pub/Sub.

• Third-party tools: Using tools like Talend or Informatica for data ingestion.

MRP stands for Material Requirements Planning, a system used for managing inventory and production schedules.

• MRP helps businesses determine the materials needed for production based on demand forecasts

• It helps in optimizing inventory levels to reduce costs and meet customer demand

• MRP software often integrates with other systems like ERP for seamless operations

Architectural design patterns are reusable solutions to common problems encountered in software design.

• Architectural design patterns provide guidelines on how to structure and organize software systems.

• Examples include MVC (Model-View-Controller), MVVM (Model-View-ViewModel), and Layered Architecture.

• They help improve the scalability, maintainability, and flexibility of software applications.

Best customer service involves actively listening to customers, addressing their needs promptly, and going above and beyond to exceed their expectations.

• Actively listen to customers to understand their needs and concerns.

• Address customer inquiries and issues promptly and effectively.

• Personalize interactions with customers to make them feel valued and appreciated.

• Go above and beyond by offering additional assistance or solutions to exceed customer expectations.

• Follow up with c...read more

FSSAI stands for Food Safety and Standards Authority of India.

• FSSAI is a government organization responsible for regulating and supervising the food safety standards in India.

• It was established under the Food Safety and Standards Act, 2006.

• FSSAI issues licenses to food businesses based on their compliance with food safety regulations.

• It conducts inspections and monitors food products to ensure they meet safety standards.

• FSSAI also educates and creates awareness among consumer...read more

Error handling in React involves creating a component to display error messages and handling errors gracefully.

• Create an ErrorBoundary component to catch errors in child components.

• Use try-catch blocks in async functions to handle errors.

• Display error messages to the user using state or props.

• Use error boundaries to prevent the entire UI from crashing due to a single error.

Merge two sorted arrays and find the median

• Merge the two arrays into one sorted array

• Calculate the median based on the length of the merged array

• Handle cases where the total length is even or odd

Use Dutch National Flag algorithm to sort the array in one pass.

• Initialize three pointers low, mid, high at start, iterate through array

• If arr[mid] is 0, swap arr[low] and arr[mid], increment low and mid

• If arr[mid] is 1, increment mid

• If arr[mid] is 2, swap arr[mid] and arr[high], decrement high

• Continue until mid crosses high

OOPs concepts refer to Object-Oriented Programming principles that focus on objects, classes, inheritance, encapsulation, and polymorphism.

• Objects: Instances of classes that encapsulate data and behavior

• Classes: Blueprint for creating objects with attributes and methods

• Inheritance: Ability for a class to inherit properties and behavior from another class

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

• Polymorphism: Ability for objects of diff...read more

Self-introduction is a brief introduction of oneself to others.

• Self-introduction should include name, background, and relevant skills.

• It should be concise and to the point.

• It should be tailored to the audience and situation.

• For example, in a job interview, focus on relevant work experience and qualifications.

• In a social setting, include hobbies and interests.

• Practice beforehand to ensure a confident delivery.

Labour laws are constantly evolving and vary by jurisdiction. It is important to stay up-to-date with changes.

• Labour laws are regulated by federal, state/provincial, and local governments

• Recent updates include changes to minimum wage, overtime pay, and sick leave policies

• COVID-19 has also impacted labour laws, with many jurisdictions implementing new regulations to protect workers

• Employers must ensure compliance with all applicable labour laws to avoid legal issues and penalt...read more

Five useful Excel shortcuts for efficient data analysis.

• Ctrl + C: Copy selected cells

• Ctrl + V: Paste copied cells

• Ctrl + Z: Undo previous action

• Ctrl + Shift + Arrow Key: Select entire data range in a direction

• Ctrl + Home: Move to cell A1

Yes, I will sell products as part of my role as a Business Development Associate.

• I will identify potential customers and their needs

• I will pitch products and services to potential customers

• I will negotiate and close deals

• I will maintain relationships with existing customers

• Examples: selling software to businesses, selling advertising space to companies

The experience you have in the field of service engineering.

• Discuss your previous roles and responsibilities in service engineering.

• Highlight any specific projects or achievements in the field.

• Mention any relevant certifications or training you have received.

• Explain how your experience makes you a strong candidate for the position.

Cost optimization in Big Query involves optimizing query performance, storage usage, and data transfer costs.

• Utilize partitioned tables to reduce query costs by scanning only relevant partitions

• Use clustering to organize data within partitions and improve query performance

• Optimize queries by using efficient SQL syntax and avoiding unnecessary operations

• Leverage caching to reduce repeated query costs

• Monitor and analyze query execution details to identify opportunities for opti...read more

Design a system for a social media platform

• Consider user authentication and authorization

• Include features for posting, liking, commenting, and sharing content

• Implement a notification system for user interactions

• Design a database schema to store user profiles, posts, comments, and relationships

• Scale the system to handle a large number of users and interactions

Frontend design involves creating the user interface of a website or application.

• Focus on user experience and usability

• Use responsive design for different screen sizes

• Implement accessibility features for users with disabilities

To find the mirror of a tree, we need to swap the left and right children of each node recursively.

• Start from the root node of the tree

• Swap the left and right children of the current node

• Recursively call the mirror function on the left and right subtrees

Our experience is extensive and diverse, spanning multiple industries and regions.

• We have worked with clients in various industries such as retail, hospitality, and healthcare.

• Our team has experience managing large-scale events and productions.

• We have successfully implemented process improvements and cost-saving measures for our clients.

• Our experience includes working with international clients and navigating cultural differences.

• We have a proven track record of delivering ex...read more

The 7 steps of sales involve prospecting, qualifying, presenting, handling objections, closing, follow-up, and referral.

• Prospecting: Identifying potential customers or leads.

• Qualifying: Determining if the prospect is a good fit for the product or service.

• Presenting: Showcasing the product or service to the prospect.

• Handling objections: Addressing any concerns or doubts the prospect may have.

• Closing: Securing the sale and finalizing the deal.

• Follow-up: Maintaining contact with...read more