40+ EPAM Interview Questions That You Must Bookmark!

EPAM Systems is a leading global digital platform engineering and software development services provider. Established in 1993, the company specializes in delivering end-to-end solutions to its customers across multiple industries, such as Financial Services, Retail & Ecommerce, Healthcare & Life Sciences, Media & Entertainment, and more.

EPAM helps organizations worldwide succeed by providing them with high-quality products and services that focus on innovation and agility. This company, which serves 1000+ clients from giant corporations and local start-ups, employs over 32K in 94 locations worldwide and has established itself as one of the most reputable enterprise technology consulting industry names.

In this article, we will be covering some important theoretical and coding questions to prepare you well for the EPAM interview process. The recruitment process at EPAM not only tests your programming abilities and practical knowledge but it is also designed to assess your soft skills too. Let's dig into the most probable technical EPAM interview questions. 

List of EPAM Interview Questions for Technical Interviews

Q1. What is an abstract class, and how does it differ from other classes in object-oriented programming?

An abstract class is an object-oriented programming construct that enables developers to create a base or parent class from which other child classes may inherit specific attributes and methods. Unlike regular classes, the members of an abstract class cannot be instantiated and are typically used as templates containing generic implementation details for use by its derived subclasses.

Q2. Describe the binary search algorithm's time complexity and usage scenarios.

The binary search algorithm uses O(log n) time complexity to find values in sorted data lists like arrays or linked lists, where n is the number of items. This makes it faster than linear search algorithms since fewer comparisons are required when searching through large datasets efficiently if they have been previously ordered via sorting techniques such as quicksort or mergesort before applying this operation to them.

Q3. How do you define a programming language as dynamic rather than static?

A programming language is said to be dynamic when a program can be modified during its running and can modify other components at runtime, avoiding the need for recompiling or redeploying an application every time changes are made.

This eliminates static languages requiring data types of variables to be declared beforehand for everything else within that codebase environment surrounding it globally, from usability testing implications involving interactive experimentation processes accordingly.

Q4. Explain the concept of dynamic programming with a simple example showing why it can benefit problem-solving tasks compared to traditional strategies such as divide and conquer or greedy algorithms?

Dynamic programming is a recursive problem-solving approach that makes use of overlapping subproblems. This technique saves time by caching or storing the solutions to previously computed problems in lookup tables, which are indexed using some part of the initial input.

Any subsequent requests for answers referencing values stored can be returned quickly as long as inputs remain unchanged and an integrity check is carried out each time it is run. Later, this practice will extend its reach across development domains in organizations that optimize performance through efficient and effective interactive user experiences, forming a never-ending journey within our global ecosystem.

Q5. What are some key features that characterize object-oriented programming?

Key features of Object-Oriented Programming:

• Encapsulation, Inheritance, and Polymorphism
• Benefits include increasing code abstraction modularity, enhanced reusability of classes, and customized user implementation.
• Wide range of applications across software development domains, from usability testing to interactive implementations in practical, real-world scenarios. 
• Continuous perpetuity as usage continues to grow with more advanced technology.

Q6 . What is an abstract method, and when would it typically be used during software development projects utilizing OOP principles?

An abstract method is a declaration found only in classes defined as abstract, meaning they cannot be instantiated. These methods have no implementation details and can, therefore, not be called directly from outside code. Child classes must inherit the definitions and provide suitable implementations for each case scenario contextually encountered within real-world usage scenarios. 

This process continues on an ever-evolving journey of universal perpetuity, visible today through multiple application landscapes involving interactive user experiences.

Q7. What is Polymorphism in Java?

In object-oriented programming, polymorphism (from Greek: polys "many" + morphē "form")) refers to the ability of a single variable or object to take on multiple forms depending on the context it appears within the program code. The most common use for polymorphism in Java is through inheritance and interfaces, where a child class can implement an interface differently from its parent class while retaining some core functionality defined by that interface.

Q8. What is EPAM Systems?

EPAM Systems is a leading global product development and software engineering solutions provider with delivery centers throughout Europe, the United States, Canada, the UK, Germany, and Japan. It provides end-to-end Digital Experience Delivery capabilities to some of the world's biggest companies, including Microsoft, Adobe and Cisco Systems.

Through its inspired teams that combine deep industry expertise with new technologies such as AI/ML projects; digital platforms; cloud services; web/mobile applications; enterprise analytics & data science initiatives for large-scale businesses, it delivers innovative solutions enabling customers to succeed today while anticipating tomorrow's challenges.

Q9. How does EPAM Systems contribute to product-based companies?

EPAM Systems provides a comprehensive platform of services, tools, and processes that help product-based companies achieve their goals efficiently. This includes assisting customers in creating solutions to address current business challenges while developing strategies for the future.

Customers benefit from increased operational agility with reduced costs through simplified management of end-to-end lifecycles and enhanced product reliability by leveraging proven engineering best practices.

Q10. What is the benefit of using static keywords while writing lines of code in EPAM Systems?

Using static keywords when writing lines of code in EPAM Systems helps simplify development tasks such as memory allocation, object manipulation, or reference tracking which can significantly reduce coding time and associated cost savings.

Additionally, developers receive an optimized runtime performance as it avoids creating duplicate objects unnecessarily due to type checking at compile time rather than during execution, like dynamic typing languages do.

Q11. How can real-life examples be incorporated into developing solutions with EPAM Systems?

Real-life examples can be incorporated into EPAM System projects using various methods such as analogies or case studies demonstrating how similar problems have been solved successfully for other organizations working with related technologies/solutions on multiple platforms (i.,e mobile applications).

Such examples provide valuable insights on what works well within specific contexts and also help identify potential pain points before they become issues further down the line, saving both money & effort spent trying to fix them later on if found out too late.

Q12. Does working on projects involving EPAM Systems require more or less coding than with other frameworks and systems?

Due to its user-friendly interface, working a business day on projects involving EPAM Systems will typically require less coding than with other frameworks and systems. It allows beginners to quickly pick up the basics and become pros without too much technical knowledge or effort. This is an advantage for companies who are short of time & resources yet need their solutions delivered faster regardless, making it one of the better options available in terms of scalability offered alongside cost savings potentials depending upon individual needs & requirements, etc.

Q13. Should dynamic arrays be used when programming within the parameters of an EPAM System project, and how should they be implemented correctly?

Dynamic arrays should be used when programming within the parameters of an EPAM System project if they meet specific criteria set out by customers, such as dynamic size alteration, memory optimization, or quick retrieval times, amongst others, so that all necessary tasks can be carried out successfully without any issues arising later down the line. 

Q14. What do you mean by Quick Sort, and which is its pivot element?

Quick Sort is an effective sorting algorithm that divides the items of an array into two groups according to their positions with respect to the chosen pivot element to arrive at its sorted representation.

The most commonly used pivot element for quick Sort is the last addressable item in the array, which proves beneficial for improved run-time and memory optimization purposes, eventually leading to improved performance benefits over traditional sorting algorithms. The piece of code in the example below showcases the implementation of the same.

Example:

public class QuickSort {public static void quickSort(int[] arr, int left, int right) {if (left < right) {int pivot = partition(arr, left, right);quickSort(arr, left, pivot - 1);quickSort(arr, pivot + 1, right);}}private static int partition(int[] arr, int left, int right) {int pivot = arr[right];int i = left - 1;for (int j = left; j < right; j++) {if (arr[j] < pivot) {i++;swap(arr, i, j);}}swap(arr, i + 1, right);return i + 1;}private static void swap(int[] arr, int i, int j) {int temp = arr[i];arr[i] = arr[j];arr[j] = temp;}public static void main(String[] args) {int[] arr = {10, 7, 8, 9, 1, 5};quickSort(arr, 0, arr.length - 1);System.out.println("Sorted Array:");for (int i : arr) {System.out.print(i + " ");}}}Output:Sorted Array:1 5 7 8 9 10

Q15. How would you target a particular element in an array using Quick Sort?

To target a particular element in an array using Quick Sort, one should set it up as the pivot point and then partition all other elements around it. Hence, they are either lower or higher than their value, respectively.

This will thus enable us to quickly identify our relevant target item no matter what fixed location of position (relative) within a given dataset it may initially have had prior process' execution initialization routine was initiated each time our procedure gets called across executing instances cycle.

Q16. Can you explain the class design to support a quick sort algorithm?

The quick sort algorithm needs a single class to contain the methods needed to implement the sorting method. Hence the class design is relatively straightforward.

This object-oriented programming type should therefore include the Constructor, Destructor, and QuickSort(int *Array) methods and an accompanying swap(int* ArrayPosition1, int* ArrayPosition2 ) helper function.

Q17. What is a class abstract, and how does it relate to the default constructors of a program/application?

In object-oriented programming, an abstract class is a class that cannot be instantiated directly. It serves as a blueprint for other classes and defines common attributes and behaviors that its subclasses can inherit and implement. An abstract class can have both abstract and non-abstract methods.

The concept of abstract classes and default constructors is not directly related. An abstract class can have constructors, including default constructors, just like any other class. The presence or absence of a default constructor in an abstract class does not have a specific relationship with the abstractness of the class itself. Default constructors are more closely related to the instantiation of classes, providing a way to create objects without actually specifying constructor arguments.

Q18. Could you explain Partition Algorithm used with the Quick Sort module?

The partition algorithm used with the Quick Sort module involves selecting a pivot element randomly or by some other means, then placing all elements less than the chosen pivot on one side.

At the same time, all those greater are placed on the opposite 'right' side, thus partitioning them into two subgroups. This is done until each group contains a single/unique element(s) synonymous to our original main array's width/size values referential contained /represented item varied quantity.

Q19. What sorting algorithms are appropriate for use with BubbleSort, and how should one select one?

The sorting algorithms for Bubble Sort implementation are mainly comprised of three sections:
1. Exchanging values within an array while comparing them to each other;
2. Iterating through every element from left to right and swapping if needed, and finally;
3. Looping until all elements have been sorted in ascending order.

When choosing a bubble sort algorithm suitable for your given use-case scenario, one should consider factors such as its ease of implementation, time & space complexities involved along with desired accuracy goals set out beforehand, cost constraints, overhead, etc.

Q20. How do you target elements specifically when working with arrays?

When working with arrays, a target element is typically accessed using an indexing system. The indexing system usually starts at 0 for the first item in the array and increments by one for each subsequent element until the nth position is reached.

Q21. What techniques can be used to identify and access array elements?

Techniques that are used to identify and access elements from an array include looping (e.g., for or while loops) to iterate through each element, using a search algorithm such as binary search, finding the maximum/minimum value in a particular subset of data or slicing out certain areas based on start-end criteria parameterized ahead of time. 

Q22. Could you explain what an element with pivot in a particular element within an array structure means?

An element with a pivot is an element within an array structure that acts as a central point for all operations to reference or use. It can also be used to sort elements in different sorting techniques, such as Quicksort and Heapsort. The pivot element helps divide any data collection so that most of it gets sorted relatively quickly.

Q23. How would you define authentication methods?

Authentication Methods are processes used to verify the identity of a user, validating that they have access to specific resources or functions in an application. This typically involves inputs like passwords, security codes, and biometric data (fingerprints or facial scans) being validated against pre-defined criteria stored securely within a system.

Q24. What is the purpose of implementing regular void method in Java?

Regular void method is primarily used for strategically declaring and defining behavior in Java programming using public static methods with return type void, which outputs no value but executes desired logic successfully within its body implementation code block.

Q25. Can you explain the abstraction implementation and abstraction types?

Abstraction implementation can be defined as providing only essential details while keeping other nonessential information hidden from actual users so that they may manipulate objects strictly based on necessity without needing full knowledge about internal mechanisms.

Abstraction types include interfaces, abstract classes, concrete classes, etc. An interface contains no method definitions. Instead, it outlines specific contracts/functionality needed for another class or object. 

• Abstract Class: Contains fields & methods, some of them incomplete and usually have at least one fully implemented.
• Concrete Classes: Have complete definitions, including unmodified language features.

Q26. What do you understand by the list interface and how it works within the Java environment?

The list interface provides a dynamic array structure allowing numerous types of element insertion and recalls along with various operation support traversing ordering, retrieving, deleting, etc., into a collections environment leveraging the same prototype instance across numerous objects for indefinite usage.

Q27. Explain the method abstract with an example.

Method abstract defines specific structured template validating child classes following strict policy defined above it & enforce uniform conventions apart from extending the existing feature set through addition if any has been proposed in actual case scenario and accordingly altering Flow control too by design itself when needed. 

Q28. List a few string operations.

Commonly used String operations include charAt(),substring() ,concat(), contains(), join() , indexOf,equalsIgnoreCase( ) method etc.

Q29. Discuss topics related to OOPS.

Core topics related to OOPS include concepts like Inheritance, polymorphism encapsulation, abstraction, data hiding, virtual functions, interfaces, overriding overloading etc., besides problem-solving paradigms, which are mainly implemented by adhering above realities during the implementation process

Q30. Explain the various stages in a bug life cycle.

The bug life cycle consists of several stages, including

• Identification – identifying and distinguishing between different types of bugs.
• Investigation – examining the code to identify where errors occur, or root causes originate.
• Develop Solution–develop a fix for the error based on your findings.
• Test Fix–testing this solution against other environments and components, with any existing tests, such as unit testing, being revisited here if necessary.
• Deployment–delivering the fixes into production instances.

Q31. What are some of the techniques used for application security testing?

Application security testing involves various techniques such as network scanning, penetration testing (both dynamic and static), source code analysis/reviews (manual & automated), vulnerability assessment checks, etc., that are used for finding potential vulnerabilities in web applications that attackers can exploit either internally or externally to gain unauthorized access over an organization’s data assets like customer records, financial information, etc.

Q32. How do non-linear data structures impact algorithm design and coding?

Non-linear data structures make it possible to store data quickly while significantly reducing algorithm complexity compared to linear structures since many lookups within non-linear structures require two jumps rather than one jump when using a linear structure due to their hierarchical nature.

Q33. How do you think using the target element keyword can help improve user accessibility on web pages?

Using a target element within link tags can help improve user accessibility on webpages by allowing developers control over page elements, specifically defining how/where links will be opened (in this case, targets).

The target element feature allows users to access better depending on their preferences. Using the target element, developers can also specify whether a link should appear in the current window or open up in a new window while keeping users on the same page, giving website administrators more control over the user's browsing experience.

Target Element, reduce hosting costs by having external documents and media (e.g., videos) hosted externally to be placed into iFrames using attributes such as target="_top" and source src="URL."

Q34. What is your experience using static void?

I have used the static void keyword in various programming languages, including Java, C++, and Visual Basic, for many years. It is usually used to declare methods that will not return any value, such as helper methods or utility functions that perform certain operations on data objects within the program, also known as subroutines or procedures.

Q35. What are the core features of Java program language?

The core features of Java program language include its object-oriented model, automatic memory management, abstraction and encapsulation, exception handling capabilities, multithreading support, and platform independence, to name a few.

Q36. Can you explain interfaces and abstract classes in core Java?

Interfaces in Core Java are collections of methods with empty bodies which need to be implemented by the classes implementing them. A specific class called an abstract, by contrast, cannot be instantiated and must instead be subclassed or extended in order to be used as a component of an application's codebase.

In particular, they act as parent classes offering reusable code for their subclasses while leaving some features unimplemented, allowing custom behavior to unique implementations derived from them.

Q37. Explain the difference between ArrayList and Vector.

1. ArrayList uses a non-synchronized approach to operations, while Vector synchronizes all of its methods for thread safety.

2. ArrayLists provide better performance when accessed from multiple threads, whereas Vectors incur an overhead due to shared lock contention across them if they are accessed concurrently from different threads.

3. Vector provides additional protection against race conditions but at the expense of increased access times in multi-threaded environments. In contrast, ArrayList has no additional safeguards but offers improved performance compared to using a Vector instance for mostly single-threaded situations.

4. Vectors provide useful legacy features like enumerate(), which aren't available in ArrayLists and offer worse implementations.

5. Arrays will be faster than vectors because they don't have synchronization overhead and costs associated with achieving this protection.

Q38. Why does Java not support multiple inheritances?

Java does not support multiple inheritances because it can cause the so-called “Diamond Problem.”

The diamond problem states that if class A extends from B and C, and both B & C extend some other class D, then the compiler has to figure out how to choose which version of D will be used when resolving a method call from A (which could cause conflicts between implementations).

This can lead to complex code with unpredictable results. For Java’s developers to guarantee consistency, they chose not to allow multiple inheritances in their language despite its potential benefits.

Q39. Explain how the stack can be implemented using the array.

The stack can be implemented using an array by consistently inserting the last element into the array to represent the top of the stack. There is a need to keep track of the number of elements currently in the stack (which we will call as size).

When a new element is added, we increment the size and insert it at that position in our array[size – 1]. To delete an item from a full-stack structure, pop() can be used, which removes and returns its argument — 'top' from the stack. This invalidates (removes) the most recently pushed item & decrements the queue/or list's current count value -- thus satisfying the LIFO principle.

Example:

import java.util.Stack;public class Main {public static void main(String[] args) {Stack<Integer> stack = new Stack<>();// Pushing elements into the stackfor (int i = 0; i < 5; ++i) {stack.push(i);}System.out.println("Stack: " + stack);// Popping elements from the stackwhile (!stack.isEmpty()) {Integer x = stack.pop();System.out.println("Popped Element: " + x);}System.out.println("Final Stack: " + stack);}}Output:Stack: [0, 1, 2, 3, 4]Popped Element: 4Popped Element: 3Popped Element: 2Popped Element: 1Popped Element: 0Final Stack: [ ]

Q40. Write a program to implement abstraction

public abstract class A {public abstract void methodOne();public void fun() {System.out.println("Fun()");// Implementing the non-abstract methods of the parent class with concrete steps}}public class B extends A {@Overridepublic void methodOne() {System.out.println("Method one implementation");}}

Q41. Explain the pass-by-value in Java.

In Java, when a method is invoked with some arguments, the value of those arguments is copied into another memory location, and this process is called a Pass-By Value. In other words, pass-by-value assigns/copies values(not references) to function parameters or variables in Java, which can be primitive data types like int and float or object reference, which points to an object containing the actual data.

This way, original data in the caller's scope will remain unaffected even if the changes made within the calling scope, i.e., inside the function body, stays valid only for that function body till execution completes.

Example:

public class Main {public static void main(String[] args) {// Object Composition = combining/creating objects from other classes as members in 1 single class & using it.Car myCar = new Car(new Type("Audi"), "A4");System.out.println(myCar);}}class Type {String type;Type(String type) {this.type = type;}}class Car {// Member Variables (fields)Type type;String model;// ConstructorCar(Type type, String model) {this.type = type;this.model = model;}@Overridepublic String toString() {return "Car [type=" + type.type + ", model=" + model + "]";}}Output: Car [type=Audi, model=A4]

Q42. Explain each keyword from the public static void main(String args[])>

public: This keyword makes the method visible to any class. Any other classes can access the method without creating an object.

Static: This keyword indicates that a particular member belongs to a certain instance, and all class instances, i.e., static members, are shared by all class objects.

Void: The void keyword indicates that this main() method does not return anything due to its execution, so this will be used when methods have no value that needs to return after completion. The void keyword also specifies in Java programming language for "unspecified" or "unknown." Therefore, whenever you use void as a function's type, then there might be nothing returned from such functions, and they may perform some tasks instead of returning something from them, which could mean either null (in the case of reference types) or Zeros (in case of primitive data-types).

main(): Main () is the starting point for JVM(java virtual machine)to start execution of java program. It signifies that when executed first line written into it will get started immediately with a further process on each instruction at the location after the previously completed code statement until the last one within the main block gets accomplished.

String args[]: The Java Virtual Machine executes the main method by calling it with a single String parameter containing any command line argument or no arguments. Thus, if you type java MyProgram one two three on the command line, then the parameters args[0] is "one," args[1] is "two," and args [2]is"three."Decision-making statements like IF THEN ELSE can be used to work out which particular argument was supplied when executing the program.

Q43. What are the Java Collections?

The framework that offers an architecture to store and deal with a collection of items is called Java Collections. The Java Collections Framework consists of interfaces and classes that can represent collections (sets, lists, bags etc.), access them by their data like maps & hashtables, organize them into stacks & queues and perform various useful operations over them such as searching & sorting.

Example: How to reverse a string?

public class ReverseString { public static void main(String[] args) { String input = "Unstop"; char[] try1=input.toCharArray();  String reverse = ""; for (int i = try1.length-1; i>=0; i--) {  reverse = reverse + try1[i]; } System.out.println("Reverse of entered string is: "+reverse);}}Output: Reverse of entered string is: potsnU

About EPAM

EPAM is a product-based company as well as offers support in understanding the necessary knowledge through technical interviews. The firm offers a range of services, including those about consumer experiences, data-driven business choices, and seamless back-end technology. Its engineering solutions include things like engineering excellence, product development, core technologies and assurance, IoT, and other such things. The company provides its services to a variety of vertical markets. 

We hope the above technical EPAM questions will help you frame your interview preparation strategy. All the best!

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