EPAM Systems Interview Questions, Process, and Tips

Use Stream API to find the kth largest element in an array of strings.

• Convert array of strings to Stream

• Sort the Stream in reverse order

• Skip k-1 elements and get the kth element

Use SQL query to find highest salary of employee in each department

• Use GROUP BY clause to group by department

• Use MAX() function to find highest salary in each group

• Join the employee table with department table to get department information

Java 8 introduced features like lambda expressions, functional interfaces, streams, and default methods.

• Lambda expressions allow you to pass functionality as an argument to a method.

• Functional interfaces have a single abstract method and can be used with lambda expressions.

• Streams provide a way to work with sequences of elements and perform aggregate operations.

• Default methods allow interfaces to have method implementa

HashMap in Java 8 uses an array of linked lists to store key-value pairs, with bucketing and resizing for efficient retrieval.

• HashMap internally uses an array of linked lists to store key-value pairs

• Each element in the array is a bucket, and each bucket can have multiple entries

• Hashing is used to determine the index of the array where the key-value pair will be stored

• In case of hash collisions, entries are stored in a ...read more

Code becomes less maintainable and can lead to unexpected behavior.

• Violates the principle of substitutability, leading to unexpected behavior in subclasses.

• May result in code that is harder to understand and maintain.

• Can lead to bugs and errors that are difficult to trace back to the violation of the principle.

• Example: If a subclass overrides a method in a way that changes its behavior significantly, it can break the L

Worked on AWS services like EC2, S3, RDS, Lambda, and more. Familiar with features like scalability, security, and cost-effectiveness.

• Worked on EC2 for scalable computing power

• Utilized S3 for secure and durable storage

• Managed RDS for relational database management

• Implemented Lambda for serverless computing

• Familiar with features like scalability, security, and cost-effectiveness

Encapsulation focuses on hiding the internal state of an object, while abstraction focuses on showing only the necessary details of an object.

• Encapsulation is the concept of bundling the data (attributes) and methods (behaviors) that operate on the data into a single unit (class).

• Abstraction is the concept of hiding the implementation details and showing only the necessary features of an object.

• Encapsulation helps in d...read more

Implicit wait is set globally for all elements, while explicit wait is applied only to specific elements.

• Implicit wait is set using driver.manage().timeouts().implicitlyWait() method

• Explicit wait is set using WebDriverWait class with ExpectedConditions

• Implicit wait is applied globally to all elements, while explicit wait is applied only to specific elements

• Implicit wait is used to wait for elements to load before perfo...read more

POM stands for Page Object Model, a design pattern used in test automation to create reusable and maintainable code by separating test scripts from web elements.

• POM helps in creating a clear separation between test code and page-specific code

• Each web page is represented as a separate class in POM

• Page Objects contain the locators and methods to interact with the elements on that page

• POM promotes code reusability and mai

Create a class, test methods, create object, and call them in code.

• Create a class with properties and methods

• Write test methods to test the functionality of the class

• Instantiate an object of the class and call its methods

Responsive design using media queries and flexible layouts to adapt frontend to different devices.

• Use media queries in CSS to apply different styles based on screen size

• Utilize responsive frameworks like Bootstrap or Foundation for pre-built responsive components

• Implement flexible layouts using percentage-based widths and max-width properties

• Optimize images for different screen resolutions using srcset and sizes attrib...read more

A closure is a function that has access to its own scope, as well as the outer scope in which it was defined.

• A closure allows a function to access variables from an outer function even after the outer function has finished executing.

• Closures are commonly used to create private variables and functions in JavaScript.

• Example: function outerFunction() { let outerVar = 'I am outer'; return function innerFunction() { console

Typescript offers advantages like static typing, improved code quality, better tooling support, and easier refactoring.

• Static typing helps catch errors at compile time

• Improved code quality due to type checking

• Better tooling support with features like code navigation and auto-completion

• Easier refactoring with the help of type annotations

• Faster development with enhanced IDE support

Architectural patterns are reusable solutions to common problems in software architecture.

• MVC (Model-View-Controller) - Separates an application into three main components: the model, the view, and the controller.

• MVVM (Model-View-ViewModel) - Similar to MVC but with a ViewModel layer that manages the state and behavior of the view.

• Flux - Unidirectional data flow pattern commonly used with React applications.

• Microservic...read more

Design patterns are reusable solutions to common problems in software design.

• Creational Patterns: Singleton, Factory, Builder

• Structural Patterns: Adapter, Decorator, Facade

• Behavioral Patterns: Observer, Strategy, Command

Yes, I have configured various parts of CI/CD pipelines.

• I have set up automated builds using tools like Jenkins or GitLab CI.

• I have configured automated testing processes within the pipeline.

• I have integrated deployment scripts to automatically deploy code to different environments.

• I have set up notifications for build status and deployment success/failure.

• I have worked on optimizing and improving the efficiency of CI/

Some popular hacker attacks include XSS (Cross-Site Scripting) and SQL Injection.

• XSS (Cross-Site Scripting) - attackers inject malicious scripts into web pages viewed by other users

• SQL Injection - attackers insert malicious SQL code into input fields to manipulate database queries

SSR improves SEO, performance, and initial load time of web applications.

• Improves SEO by serving fully rendered HTML to search engine crawlers

• Enhances performance by reducing time to first paint and time to interactive

• Faster initial load time for users, especially on slower network connections

• Better support for social media crawlers and web scrapers

• Enables content to be visible to users even if JavaScript is disabled

Merge two intervals by sorting and iterating through the intervals.

• Sort the intervals based on the start value.

• Iterate through the intervals and merge overlapping intervals.

• Return the merged intervals.

Test plan and strategy outline the approach for testing a software application.

• Test plan includes objectives, scope, resources, schedule, and risks.

• Test strategy defines testing approach, techniques, tools, and responsibilities.

• Both documents are essential for successful testing and quality assurance.

• Example: Test plan may include test cases, test scenarios, and test data.

• Example: Test strategy may outline automation t...read more

SQL query to find unique records, truncate, abort, DML commands

• To find unique records in SQL, you can use the DISTINCT keyword in your SELECT statement.

• Truncate is a SQL command used to quickly delete all records from a table, but it cannot be rolled back.

• Abort is a command used to cancel a transaction in SQL.

• DML (Data Manipulation Language) commands in SQL include INSERT, UPDATE, DELETE.

To find the missing number from a list, calculate the sum of all numbers in the list and subtract it from the expected sum of the list.

• Calculate the sum of all numbers in the list using a loop or a built-in function.

• Calculate the expected sum of the list using the formula n*(n+1)/2, where n is the length of the list.

• Subtract the sum of the list from the expected sum to find the missing number.

Optimizing Spark performance involves tuning configurations, partitioning data, caching, and using efficient transformations.

• Tune Spark configurations for memory allocation, parallelism, and resource management.

• Partition data properly to distribute work evenly across nodes and minimize shuffling.

• Cache intermediate results in memory to avoid recomputation.

• Use efficient transformations like map, filter, and reduceByKey i...read more