100+ Ele5 Solutions Interview Questions and Answers

Convert a string of multiple lines with 'n' words to multiple arrays of fixed size without overlap.

• Split the string into individual words

• Create arrays of fixed size 'k' and distribute words evenly

• Handle cases where the number of words is not divisible by 'k'

ASP.NET page life cycle and events in it and how page will be rendered.

• Page life cycle includes events like Init, Load, PreRender, and Unload.

• During Init, controls are initialized and their properties are set.

• During Load, controls are loaded with data and their events are fired.

• During PreRender, the page is prepared for rendering.

• During Unload, resources are released.

• Page is rendered using HTML, CSS, and JavaScript.

• Rendered page is sent to the client's browser for display.

As a Product Owner of a Tea shop, what questions will you ask a customer who wants to place a bulk order for tea?

• What type of tea do you prefer?

• How much tea do you need?

• What is the purpose of the bulk order?

• Do you have any specific requirements or preferences?

• When do you need the tea delivered?

• What is your budget for the bulk order?

Gradient descent is an optimization algorithm used to minimize the cost function of a machine learning model.

• Gradient descent is used to update the parameters of a model to minimize the cost function.

• It follows the direction of steepest descent, which is the negative gradient of the cost function.

• The learning rate determines the step size of the algorithm.

• The formula for gradient descent is: theta = theta - alpha * (1/m) * sum((hypothesis - y) * x)

• The cost function should be ...read more

Sort employees by salary and department

• Create a comparator function to compare salary and department

• Use the comparator function with the sort() method on the employee stream

• Return the sorted employee stream

Authentication is the process of verifying the identity of a user or system.

• There are three types of authentication: something you know (passwords, PINs), something you have (smart cards, tokens), and something you are (biometrics).

• Two-factor authentication combines two of these types for added security.

• Authentication protocols include OAuth, OpenID Connect, and SAML.

• Authentication can also be classified as single-factor, multi-factor, or risk-based.

• Common authentication meth...read more

Use SQL query to find columns with timestamp data type in a table.

• Use a SQL query like 'SHOW COLUMNS FROM table_name WHERE Type = 'timestamp''

• Alternatively, query the information_schema.columns table for column data types

• Check for variations of timestamp data types like datetime, timestamp, etc.

Unacknowledged messages in pubsub can be handled by implementing retries, dead letter queues, and monitoring mechanisms.

• Implement retries for unacknowledged messages to be redelivered.

• Use dead letter queues to store messages that repeatedly fail to be processed.

• Set up monitoring mechanisms to track unacknowledged messages and identify potential issues.

MVC URL routing allows for custom URL definitions in ASP.NET

• MVC URL routing maps URLs to controller actions

• Normal URL definition uses query strings to pass parameters

• MVC URL routing is more SEO-friendly

• MVC URL routing can be configured in RouteConfig.cs file

• Example: /products/category/electronics maps to ProductsController's Category action with 'electronics' parameter

Redux is a predictable state container for JavaScript apps.

• Redux is a state management library for JavaScript applications.

• It helps in managing the state of an application in a predictable way.

• Redux follows a unidirectional data flow pattern.

• Context API is a built-in feature of React that can be used for state management, but it is not as powerful as Redux.

• ES6 features include arrow functions, template literals, destructuring, classes, and more.

• Rest and Spread are both ES6 fe...read more

Find the second index of 'l' in the string 'Hello'.

• Use the find() method to find the first index of 'l'.

• Use the find() method again starting from the index after the first 'l' to find the second index.

• Handle cases where the first 'l' is not found or there is no second 'l'.

Use the split() method to convert a string with multiple lines into a list of strings.

• Use the split() method with the newline character '\n' as the delimiter to split the string into a list of strings.

• Example: 'Hello\nWorld\n' -> ['Hello', 'World']

Program to find 2nd largest number in array

• Sort the array in descending order and return the 2nd element

• Initialize two variables, largest and secondLargest, and iterate through the array to find the two largest numbers

• Use a priority queue to keep track of the two largest numbers

count(*) counts all rows in a table, while count(1) counts the number of non-null values in a specific column.

• count(*) counts all rows in a table

• count(1) counts the number of non-null values in a specific column

• count(*) is generally used when you want to count all rows in a table, while count(1) is used when you want to count non-null values in a specific column

Traversal conditions for a Doubly Linked List involve moving forward and backward through each node.

• Start at the head node and move to the next node by following the 'next' pointer.

• To traverse backward, start at the tail node and move to the previous node by following the 'prev' pointer.

• Continue this process until reaching the end of the list.

Implementing incremental load in a table involves updating only new or changed data without reloading the entire dataset.

• Identify a column in the table that can be used to track changes, such as a timestamp or a version number

• Use this column to filter out only the new or updated records during each load

• Merge the new data with the existing data in the table using SQL queries or ETL tools

• Ensure data integrity by handling any conflicts or duplicates that may arise during the inc...read more

MVC separates concerns, promotes code reusability, and enhances testability.

• 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 by separating concerns.

• MVC enhances testability by allowing for easier unit testing of individual components.

• MVC allows for easier maintenance and ...read more

Singleton class is a class that can only have one instance, while HashMap is not thread-safe but ConcurrentHashMap is.

• Singleton class restricts instantiation to one object, ensuring a single instance throughout the application.

• HashMap allows multiple threads to access and modify it concurrently, which can lead to data corruption in a multi-threaded environment.

• ConcurrentHashMap is thread-safe and allows multiple threads to read and write concurrently without the need for exte...read more

Handled conflicts in code merging and resource allocation.

• Used version control systems like Git to manage code merging conflicts.

• Communicated with team members to resolve resource allocation conflicts.

• Prioritized tasks and resources based on project requirements.

• Implemented agile methodologies to minimize conflicts and improve collaboration.

• Documented conflict resolution processes for future reference.

To check if a linkedlist is palindrome or not

• Traverse the linkedlist and push each element into a stack

• Traverse the linkedlist again and compare each element with the popped element from the stack

• If all elements match, then the linkedlist is palindrome

I primarily use the MVC design pattern for its clear separation of concerns and ease of maintenance.

• MVC (Model-View-Controller) - separates data, presentation, and user input into three interconnected components

• Singleton - ensures a class has only one instance and provides a global point of access to it

• Factory - creates objects without specifying the exact class of object that will be created

• Observer - defines a one-to-many dependency between objects so that when one object c...read more

State management in ASP.Net refers to the process of storing and retrieving data between HTTP requests.

• ASP.Net provides various techniques for state management such as ViewState, Session, Application, and Cache.

• ViewState is used to store page-specific data, Session is used to store user-specific data, Application is used to store application-level data, and Cache is used to store frequently accessed data.

• State management is important for maintaining the state of an applicatio...read more

Reverse a string without using any inbuilt method.

• Iterate through the string from the last character to the first

• Create a new string and append each character to it

• Return the reversed string

var, let, and const are used for variable declaration in JavaScript, differing in scope, hoisting, and mutability.

• var is function-scoped or globally scoped, while let and const are block-scoped.

• let allows variable reassignment, whereas const does not allow reassignment after initial assignment.

• var is hoisted, meaning it can be used before its declaration, while let and const are not hoisted in the same way.

• Example: var x = 1; let y = 2; const z = 3; y = 4; // valid, z = 5; //...read more

Flexbox is for one-dimensional layouts, while Grid is for two-dimensional layouts in CSS.

• Flexbox is designed for layout in a single direction (row or column). Example: Aligning items in a navbar.

• Grid allows for layout in both rows and columns simultaneously. Example: Creating a complex web page layout.

• Flexbox is great for distributing space within a container. Example: Equal spacing between buttons.

• Grid is better for creating overall page structure. Example: Defining areas fo...read more

Use the DISTINCT keyword in a SELECT statement to remove duplicate rows from a table.

• Use the DISTINCT keyword in a SELECT statement to retrieve unique rows

• Use the GROUP BY clause with appropriate columns to remove duplicates

• Use the ROW_NUMBER() function to assign a unique row number to each row and then filter out rows with row number greater than 1

Remove duplicates from 2D array of strings

• Use nested loops to compare each element

• Create a new array to store unique strings

• Use HashSet to remove duplicates

Program to find the prefix of OL in an array of strings

• Loop through each string in the array

• Check if the first two characters are 'OL'

• If yes, add the string to a new array of prefixes

• Return the array of prefixes

I utilized several design patterns in my projects to enhance code maintainability and scalability.

• Singleton Pattern: Ensured a single instance of a configuration manager throughout the application.

• Factory Pattern: Used to create different types of user objects based on user roles, promoting loose coupling.

• Observer Pattern: Implemented for event handling, allowing multiple components to react to changes in the state of an object.

• Strategy Pattern: Employed to define a family of...read more

Drop removes a table from the database, truncate removes all rows from a table, and delete removes specific rows from a table.

• DROP: Removes the entire table structure and data from the database.

• TRUNCATE: Removes all rows from a table but keeps the table structure.

• DELETE: Removes specific rows from a table based on a condition.

• Example: DROP TABLE table_name;

• Example: TRUNCATE TABLE table_name;

• Example: DELETE FROM table_name WHERE condition;

Microservice Design Pattern structures applications as a collection of loosely coupled services, enhancing scalability and maintainability.

• Microservices are independently deployable services that communicate over a network.

• Each microservice focuses on a specific business capability, e.g., user management or payment processing.

• Spring Boot simplifies the development of microservices with embedded servers and auto-configuration.

• Kafka is often used for asynchronous communication ...read more

OOPs concept refers to Object-Oriented Programming principles like inheritance, encapsulation, polymorphism, and abstraction.

• Inheritance: Reusing code and creating a hierarchy of classes

• Encapsulation: Hiding the internal implementation details of a class

• Polymorphism: Ability to use a single interface for different data types or objects

• Abstraction: Showing only necessary details and hiding unnecessary details

Postback events are server-side events triggered by user actions on a web page.

• Postback events occur when a user interacts with a web page and the page sends a request back to the server for processing.

• Examples of postback events include clicking a button, selecting an item from a dropdown list, or submitting a form.

• Postback events can be used to update the page content without requiring a full page refresh.

• ASP.NET is a framework that uses postback events extensively.

Subjects are multicast observables that can emit values, while observers are consumers that react to those emitted values.

• A Subject can emit values to multiple subscribers, while an Observer receives values from a Subject.

• Example of Subject: const subject = new Subject(); subject.next('Hello');

• Example of Observer: const observer = { next: (value) => console.log(value); }; subject.subscribe(observer);

• Subjects can act as both an Observable and an Observer, while Observers only ...read more

Components are self-contained UI elements, while directives are used to extend HTML behavior.

• Components are a complete UI element with a template, styles, and logic (e.g., <app-header>).

• Directives are used to manipulate the DOM or enhance existing elements (e.g., ngIf, ngFor).

• Components can have their own view and encapsulated styles, while directives do not have their own view.

• Components are typically used for building reusable UI elements, while directives are used for beha...read more

Asynchronous behavior in JavaScript allows non-blocking operations, enhancing performance and user experience.

• 1. Callbacks: Functions passed as arguments to handle asynchronous results. Example: setTimeout(() => console.log('Done!'), 1000);

• 2. Promises: Objects representing eventual completion (or failure) of an asynchronous operation. Example: const promise = new Promise((resolve, reject) => { /* ... */ });

• 3. Async/Await: Syntactic sugar over promises, allowing writing asynch...read more

HTML5 introduced new semantic elements to enhance the structure and meaning of web content.

• header: Represents introductory content or navigational links. Example: <header><h1>Site Title</h1></header>

• footer: Defines footer for a section or page. Example: <footer><p>© 2023 Company Name</p></footer>

• article: Represents a self-contained composition. Example: <article><h2>Article Title</h2><p>Content...</p></article>

• section: Defines a thematic grouping of content. Example: <section...read more

The doctype declaration informs the browser about the HTML version being used, ensuring proper rendering of the document.

• Defines the document type and version of HTML (e.g., <!DOCTYPE html> for HTML5).

• Helps browsers render the page correctly by switching to standards mode.

• Prevents browsers from entering quirks mode, which can lead to inconsistent rendering.

• Affects how CSS and JavaScript are interpreted by the browser.

ASP.Net cache is a feature that stores frequently accessed data in memory to improve application performance.

• ASP.Net cache is available in two types: in-memory cache and distributed cache.

• In-memory cache stores data in the memory of the web server.

• Distributed cache stores data in a separate cache server that can be accessed by multiple web servers.

• ASP.Net cache can be used to store data such as database query results, page output, and application configuration settings.

• Cache ...read more

REST, Spring annotations, Spring Boot, and 12 Factor of microservices

• REST is an architectural style for building web services

• Spring annotations like @primary, @qualifier, and @component are used for dependency injection

• Spring Boot is a framework for building stand-alone, production-grade Spring-based applications

• 12 Factor is a methodology for building scalable and maintainable microservices

Supervised machine learning is a type of ML where the algorithm learns from labeled data. Random forest is used over normal decision tree for better accuracy and to avoid overfitting.

• Supervised ML learns from labeled data to make predictions on new data

• Random forest is an ensemble learning method that uses multiple decision trees to improve accuracy

• Random forest is preferred over normal decision tree to avoid overfitting and improve accuracy

• Random forest is used in various ap...read more

Spring Boot annotations simplify configuration and enhance the development of Java applications.

• @SpringBootApplication: Combines @Configuration, @EnableAutoConfiguration, and @ComponentScan.

• @RestController: Indicates that the class is a controller where every method returns a domain object instead of a view.

• @RequestMapping: Used to map web requests to specific handler methods.

• @Autowired: Enables automatic dependency injection.

• @Value: Injects values into fields from applicatio...read more

Hadoop is an open-source framework used for distributed storage and processing of large data sets across clusters of computers.

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

• It allows for parallel processing of large datasets across multiple nodes in a cluster.

• Hadoop is scalable, fault-tolerant, and cost-effective for handling big data.

• Popular tools like Apache Hive, Apache Pig, and Apache Spark can be integrated with Hadoop ...read more

OOP in Python is based on four main principles: encapsulation, inheritance, polymorphism, and abstraction.

• Encapsulation: Bundling data and methods that operate on the data within one unit (class). Example: class Dog with attributes and methods.

• Inheritance: Mechanism to create a new class from an existing class, inheriting its properties. Example: class Bulldog inherits from class Dog.

• Polymorphism: Ability to use a common interface for different data types. Example: method ove...read more

AoT (Ahead of Time) is a compilation technique used in Microsoft Azure to improve application performance.

• AoT compiles code before it is executed, resulting in faster startup times and reduced memory usage.

• It is commonly used in Azure Functions and Azure Web Apps.

• AoT can also improve security by detecting potential vulnerabilities during compilation.

• It is different from Just-in-Time (JIT) compilation, which compiles code during runtime.

• AoT can be used with multiple programmin...read more

Probability density function is for continuous random variables while mass function is for discrete random variables.

• Probability density function gives the probability of a continuous random variable taking a certain value within a range.

• Mass function gives the probability of a discrete random variable taking a certain value.

• Probability density function integrates to 1 over the entire range of the random variable.

• Mass function sums to 1 over all possible values of the random ...read more

Flow is a cold asynchronous data stream, Channel is a hot asynchronous data stream. StateFlow is a hot asynchronous data stream with a state, SharedFlow is a hot asynchronous data stream without a state.

• Flow is a cold asynchronous data stream that emits values one by one.

• Channel is a hot asynchronous data stream that can have multiple subscribers.

• StateFlow is a hot asynchronous data stream that retains the most recent value and emits it to new subscribers.

• SharedFlow is a hot ...read more

Minimum swaps needed to arrange all similar elements together in an array of strings.

• Count the frequency of each element in the array.

• Find the maximum frequency element and its index.

• Calculate the number of swaps needed to move all similar elements together.

• Repeat the above steps for all unique elements in the array.

• Add up the number of swaps needed for each unique element to get the total number of swaps needed.

I have used services like BigQuery, Dataflow, Pub/Sub, and Cloud Storage in GCP.

• BigQuery for data warehousing and analytics

• Dataflow for real-time data processing

• Pub/Sub for messaging and event ingestion

• Cloud Storage for storing data and files

Optimizing dags involves reducing unnecessary tasks, parallelizing tasks, and optimizing resource allocation.

• Identify and remove unnecessary tasks to streamline the workflow.

• Parallelize tasks to reduce overall execution time.

• Optimize resource allocation by scaling up or down based on task requirements.

• Use caching and memoization techniques to avoid redundant computations.

• Implement data partitioning and indexing for efficient data retrieval.

Improving website performance involves optimizing code, reducing server requests, using caching, and optimizing images.

• Optimize code by minifying CSS, JavaScript, and HTML

• Reduce server requests by combining files and using asynchronous loading

• Utilize caching techniques like browser caching and server-side caching

• Optimize images by resizing, compressing, and using modern image formats like WebP

A dictionary sorted in ascending order based on keys.

• Create a dictionary with key-value pairs

• Use the sorted() function to sort the dictionary based on keys

• Convert the sorted dictionary into a list of tuples

• Use the dict() constructor to create a new dictionary from the sorted list of tuples

Late binding or dynamic binding is a technique in which the method call is resolved at runtime rather than compile time.

• In late binding, the type of the object is determined at runtime.

• It allows for more flexibility in code as it can handle different types of objects.

• Dynamic keyword is used for late binding in C#.

• Example: using reflection to invoke a method on an object whose type is not known until runtime.

Accumulators are shared variables that are updated by worker nodes and can be used for aggregating information across tasks.

• Accumulators are used for implementing counters and sums in Spark.

• They are only updated by worker nodes and are read-only by the driver program.

• Accumulators are useful for debugging and monitoring purposes.

• Example: counting the number of errors encountered during processing.

Display a list of items using Pagination concept in React

• Create a list of items to display

• Implement pagination logic to display a limited number of items per page

• Add navigation buttons to switch between pages

Count duplicates in array of strings

• Create a dictionary to store the count of each string

• Loop through the array and increment the count in dictionary

• Loop through the dictionary and count the duplicates

• Return the count of duplicates

ChangeDetectionStrategy in Angular determines how the framework checks for changes in component data.

• Angular provides two strategies: Default and OnPush.

• Default strategy checks all components in the component tree for changes.

• OnPush strategy only checks the component when its input properties change or an event occurs.

• Using OnPush can improve performance by reducing the number of checks.

• Example: @Component({ changeDetection: ChangeDetectionStrategy.OnPush })

Inline functions are functions that are expanded in place at the call site, while high-order functions are functions that can take other functions as parameters or return them.

• Inline functions are expanded in place at the call site to improve performance.

• High-order functions can take other functions as parameters or return them.

• Example of high-order function: map() function in Kotlin.

Query to find duplicate data using SQL

• Use GROUP BY and HAVING clause to identify duplicate records

• Select columns to check for duplicates

• Use COUNT() function to count occurrences of each record

Top is used to select the first few rows from a dataset, while limit is used to restrict the number of rows returned in a query.

• Top is commonly used in SQL Server, while limit is commonly used in MySQL.

• Top is used with the SELECT statement in SQL Server to limit the number of rows returned, while limit is used in MySQL to restrict the number of rows returned.

• Example: SELECT TOP 5 * FROM table_name; (SQL Server) vs. SELECT * FROM table_name LIMIT 5; (MySQL)

Database automation can be performed using tools and scripts to automate tasks such as data migration, backups, and testing.

• Use tools like SQL Server Management Studio, Oracle SQL Developer, or MySQL Workbench to automate tasks

• Write scripts using languages like SQL, Python, or PowerShell to automate tasks

• Automate data migration tasks using tools like AWS Database Migration Service or Azure Database Migration Service

• Automate backups using tools like SQL Server Backup and Resto...read more

Namespace is a container that holds identifiers (names) used to avoid naming conflicts.

• Namespace is created at different moments and has different lifetimes.

• Python implements namespaces as dictionaries.

• There are four types of namespaces in Python: built-in, global, local, and non-local.

• Namespaces can be accessed using the dot (.) operator.

• Example: 'import math' creates a namespace 'math' that contains all the functions and variables defined in the math module.

Design a Parking Management System for efficient parking space allocation and management.

• Implement a system to track available parking spaces in real-time.

• Include features for booking parking spots in advance.

• Incorporate a payment system for parking fees.

• Utilize sensors or cameras for monitoring parking space occupancy.

• Develop a user-friendly interface for customers to easily navigate and use the system.

Convert a smallcased string to all capital case.

• Use the toUpperCase() method to convert the string to uppercase.

• Assign the result to a new variable or overwrite the original string.

• Make sure to handle any non-alphabetic characters appropriately.

Synchronization is the coordination of multiple processes to ensure they work together effectively.

• Synchronization is important in multi-threaded applications to prevent race conditions and ensure data consistency.

• We can handle synchronization using techniques like locks, semaphores, and monitors.

• For example, in Java, we can use synchronized keyword or ReentrantLock class to achieve synchronization.

• Another example is using wait() and notify() methods in Java to coordinate thr...read more

ADD and COPY are Dockerfile instructions used to copy files and directories into a Docker image, but they have some key differences.

• ADD allows for URLs and automatically extracts compressed files, while COPY only works with local files

• COPY is recommended for copying local files and directories into an image, while ADD is more versatile but can be less predictable

• ADD can be used to download files from the internet and add them to the image, while COPY cannot

A blocking queue is a queue that blocks when attempting to dequeue from an empty queue or enqueue to a full queue.

• BlockingQueue interface is a part of java.util.concurrent package

• It provides thread-safe operations for put() and take() methods

• Examples: ArrayBlockingQueue, LinkedBlockingQueue, PriorityBlockingQueue

A data warehouse is a large, centralized repository of data that is used for reporting and analysis.

• Data is extracted from various sources and transformed into a common format

• Data is organized into dimensions and fact tables

• Designed for querying and analysis rather than transaction processing

• Supports complex queries and reporting

• Examples include Amazon Redshift, Google BigQuery, and Microsoft Azure SQL Data Warehouse

To delete a column from a table, use the ALTER TABLE command.

• Use the ALTER TABLE command followed by DROP COLUMN to delete a column from a table.

• Specify the name of the column you want to delete after the DROP COLUMN keyword.

• Make sure to carefully consider the impact of deleting a column on the data and any dependent objects.

Check if pair sum exists in the array using a hash map.

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

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

• Return true if a pair sum exists, otherwise return false.

I take design decisions by considering user needs, research data, industry trends, and feedback.

• Understand user needs through research and user testing

• Analyze industry trends and best practices

• Consider feedback from stakeholders and users

• Iterate on designs based on data and feedback

• Prioritize usability and accessibility

Some annotations used in Spring Boot projects are @RestController, @Autowired, @RequestMapping, @Service, @Component, @Repository.

• @RestController - Used to define RESTful web services.

• @Autowired - Used for automatic dependency injection.

• @RequestMapping - Used to map web requests to specific handler methods.

• @Service - Used to indicate that a class is a service.

• @Component - Used to indicate that a class is a Spring component.

• @Repository - Used to indicate that a class is a repo...read more

Decorators are functions that modify the behavior of other functions without changing their source code.

• Decorators are denoted by the '@' symbol followed by the decorator function name.

• They can be used to add functionality to a function, such as logging or timing.

• Decorators can also be used to modify the behavior of a class or method.

• They are commonly used in web frameworks like Flask and Django.

• Examples of built-in decorators in Python include @staticmethod and @classmethod.

Map, TreeMap and Set are data structures used in Java to store and manipulate collections of objects.

• Map is an interface that maps unique keys to values.

• TreeMap is a class that implements the Map interface and stores its elements in a sorted order.

• Set is an interface that stores unique elements.

• TreeSet is a class that implements the Set interface and stores its elements in a sorted order.

• All three data structures are part of the Java Collections Framework.

DevOps is needed in an organization to improve collaboration between development and operations teams, increase efficiency, and deliver high-quality software faster.

• Improves collaboration between development and operations teams

• Increases efficiency in software development and deployment processes

• Helps in delivering high-quality software faster

• Automates repetitive tasks to reduce manual errors

• Facilitates continuous integration and continuous delivery (CI/CD) practices

• Enhances ...read more

GCP main components include Compute Engine, Cloud Storage, BigQuery, and Dataflow for various uses.

• Compute Engine - Virtual machines for running workloads

• Cloud Storage - Object storage for storing data

• BigQuery - Data warehouse for analytics

• Dataflow - Stream and batch processing of data

Template-driven forms in Angular use HTML templates to manage form inputs and validation, simplifying form handling.

• Built using Angular's directives like ngModel for two-way data binding.

• Forms are defined in the template, making them easy to read and maintain.

• Validation is handled using Angular's built-in validators, such as required or minlength.

• Example: <input [(ngModel)]='user.name' required /> binds the input to the user object.

• Form submission can be handled using (ngSubm...read more

Pub/sub is a messaging pattern where senders (publishers) of messages do not program the messages to be sent directly to specific receivers (subscribers).

• Pub/sub stands for publish/subscribe.

• Publishers send messages to a topic, and subscribers receive messages from that topic.

• It allows for decoupling of components in a system, enabling scalability and flexibility.

• Examples include Apache Kafka, Google Cloud Pub/Sub, and MQTT.

Algorithm to solve Sudoku puzzle

• Create a 9x9 grid to represent the puzzle

• Fill in known numbers

• For each empty cell, try numbers 1-9 until a valid number is found

• Backtrack if no valid number can be found

• Repeat until all cells are filled

Remove repeated letters from a given string

• Iterate through the string and keep track of seen letters

• Use a set to store unique letters and build the result string

Springboot can be implemented using any IDE that supports Java development.

• Spring Tool Suite (STS) is a popular IDE for Springboot development

• IntelliJ IDEA also has good support for Springboot

• Eclipse with Spring Tooling plugin can also be used

• IDEs provide features like auto-completion, debugging, and deployment

• Maven or Gradle can be used as build tools for Springboot projects

To find the second maximum number in a list, sort the list in descending order and return the second element.

• Sort the list in descending order

• Return the second element in the sorted list

Find the frequency of characters in an array of strings.

• Iterate through each string in the array

• For each character in the string, increment its count in a hashmap

• Return the hashmap with character frequencies

Git commit records changes to the repository, merge combines changes from different branches, and rebase moves changes to a new base commit.

• Git commit saves changes to the local repository with a message describing the changes made.

• Git merge combines changes from different branches into the current branch.

• Git rebase moves changes from one branch to another by applying each commit from the source branch to the target branch.

k-Nearest Neighbors algorithm is a non-parametric classification algorithm.

• k-NN algorithm is based on the principle of finding k-nearest neighbors to a given data point and classifying it based on the majority class of its neighbors.

• It is a lazy learning algorithm as it does not require any training data to build a model.

• The value of k is an important parameter in k-NN algorithm and can be determined using cross-validation.

• k-NN algorithm can be used for both classification an...read more

JavaScript (js) is a programming language commonly used for web development, while React is a JavaScript library for building user interfaces.

• JavaScript (js) is a versatile programming language used for both front-end and back-end development.

• React is a popular JavaScript library developed by Facebook for building interactive user interfaces.

• React allows for the creation of reusable UI components, making it easier to maintain and update code.

• React uses a virtual DOM for effic...read more

Using Java8 to filter vowels from an array of strings

• Use Java8 stream and filter to iterate through each string in the array

• Use a lambda expression to check if each character is a vowel

• Collect the filtered strings into a new array

Angular guards are interfaces that control access to routes in an Angular application.

• Types of guards: CanActivate, CanActivateChild, CanDeactivate, Resolve, and CanLoad.

• CanActivate: Determines if a route can be activated. Example: Checking user authentication.

• CanDeactivate: Checks if a user can leave a route. Example: Unsaved changes warning.

• Resolve: Pre-fetches data before activating a route. Example: Fetching user data before navigating.

• CanLoad: Controls if a module can be...read more

JOIN query to retrieve country and employee name

• Use JOIN keyword to combine data from multiple tables

• Specify the columns to select from each table

• Use ON keyword to specify the relationship between the tables

Spark architecture is a distributed computing framework that consists of a driver program, cluster manager, and worker nodes.

• Spark architecture includes a driver program that manages the execution of the Spark application.

• It also includes a cluster manager that allocates resources and schedules tasks on worker nodes.

• Worker nodes are responsible for executing the tasks and storing data in memory or disk.

• Spark architecture supports fault tolerance through resilient distributed ...read more

Common problem in Java 8 stream is improper use of terminal operations.

• Terminal operations like forEach() and collect() should be used after intermediate operations like filter() and map().

• Improper use of parallel streams can also lead to performance issues.

• Stream pipeline should be short and focused on a single task.

• Avoid using streams for small collections or when performance is critical.

Types of jobs in Kotlin coroutine include launch, async, withContext, and runBlocking.

• launch: starts a new coroutine without blocking the current thread

• async: starts a new coroutine and returns a Deferred object with a result

• withContext: switches the coroutine context within a coroutine

• runBlocking: blocks the current thread until the coroutine inside it is completed

Custom priority queue implementation

• Define a data structure to hold the elements and their priorities

• Implement methods to add, remove and peek elements based on priority

• Use a heap or binary tree to maintain the priority order

• Consider edge cases like empty queue and duplicate elements

Builder design pattern is a creational design pattern used to construct complex objects step by step.

• Builder pattern separates the construction of a complex object from its representation.

• It allows the same construction process to create different representations of the object.

• Useful when there are multiple ways to construct an object or when the object creation process is complex.

• Example: StringBuilder in Java allows you to build strings by appending characters or other stri...read more

Flow lifecycle aware means using Kotlin Flow with lifecycle awareness in Android development.

• Flow lifecycle aware helps manage data streams in Android apps

• It ensures that data emissions are only observed when the lifecycle is in the appropriate state

• Example: Using Flow with LiveData to update UI components based on lifecycle events

Backtracking is a technique to solve problems by trying out different solutions and undoing them if they fail.

• Backtracking is used when we need to find all possible solutions to a problem.

• It involves trying out different solutions and undoing them if they fail.

• It is often used in problems involving permutations, combinations, and graph traversal.

• Examples include solving Sudoku puzzles, finding all possible paths in a maze, and generating all possible permutations of a set of ...read more

Hashmap is a data structure that stores key-value pairs and uses hashing to retrieve values quickly.

• Hashmap uses an array to store the key-value pairs

• The keys are hashed to generate an index in the array

• If two keys hash to the same index, a linked list is used to store the values

• Retrieving a value involves hashing the key to find the index and then traversing the linked list if necessary