Verifone Front end Engineer Interview Questions and Answers

Polymorphism is the ability of an object to take on many forms. Constructors and destructors are special methods in classes.

• Polymorphism allows objects to be treated as instances of their own class or as instances of their parent class.

• Constructors are used to initialize objects when they are created. Destructors are used to clean up after an object when it is destroyed.

• Classes are templates for creating objects. They ...read more

Encapsulation is the process of hiding implementation details and exposing only the necessary information to the user.

• Encapsulation is achieved through access modifiers like public, private, and protected.

• It helps in achieving data abstraction and information hiding.

• Encapsulation provides better control over the data and prevents unauthorized access.

• Example: A class with private variables and public methods to access t...read more

Remove duplicates in linked lists

• Traverse the linked list and keep track of visited nodes using a hash table

• If a node is already visited, remove it from the linked list

• Time complexity: O(n), Space complexity: O(n)

Mergesort is a divide-and-conquer algorithm that sorts an array by dividing it into two halves, sorting each half, and merging them.

• Divide the array into two halves

• Sort each half recursively

• Merge the two sorted halves

• Repeat until the entire array is sorted

• Example: ['apple', 'banana', 'cherry', 'date'] -> ['apple', 'banana', 'cherry', 'date'] -> ['apple', 'banana'], ['cherry', 'date'] -> ['apple'], ['banana'], ['cherry'...read more

Reverse a given string

• Create an empty string

• Iterate through the original string in reverse order

• Append each character to the empty string

• Return the reversed string

Reverse words in a string

• Split the string into an array of words

• Reverse the array

• Join the array into a string

Check if a string is palindrome or not

• Reverse the string and compare with original

• Compare characters from start and end of string

• Ignore spaces and punctuation marks while comparing

I am a software engineer with experience in developing web applications and a passion for problem-solving.

• Experienced in developing web applications using technologies such as HTML, CSS, JavaScript, and React

• Proficient in programming languages such as Java and Python

• Skilled in problem-solving and troubleshooting

• Strong communication and collaboration skills

• Passionate about staying up-to-date with the latest technologies

GATE is not my preferred choice as I am more interested in software development than research.

• I am more interested in practical application of software development than theoretical research

• I believe my skills and interests align better with software engineering roles

• I have researched and found that software engineering roles do not require a GATE qualification

I prefer open-source technologies and have more experience with them.

• I have more experience with open-source technologies like Linux and Python.

• I believe in the benefits of open-source software for collaboration and innovation.

• I am not opposed to using MS technologies if they are the best fit for the project.

• However, I prefer to work with technologies that align with my values and experience.

Diebold offers challenging work and opportunities for growth in the software engineering field.

• Diebold has a strong reputation in the industry

• The company offers a diverse range of projects and technologies to work on

• There are opportunities for career growth and development

• The work is challenging and rewarding

• Diebold values innovation and creativity in its employees

Software is the future and ECE has a strong foundation in programming and problem-solving.

• ECE curriculum includes programming courses

• Software development is a growing industry

• Programming skills are transferable across fields

• Interest in software development and problem-solving

• Opportunities to work on software projects during ECE studies

To find the maximum water pond formed between buildings.

• Identify the lowest point between the buildings.

• Calculate the area of the pond using the distance between the buildings and the depth of the pond.

• Consider any obstacles or uneven ground that may affect the pond's shape.

• Use a surveying tool or satellite imagery to get accurate measurements.

• Take into account any drainage systems or natural water flow that may affect

Design a dictionary using trie with insert, update and delete operations.

• Implement a Trie data structure with nodes containing a character and a boolean flag to indicate end of word

• For insert operation, traverse the trie and add nodes for each character in the word

• For update operation, delete the existing word and insert the updated word

• For delete operation, mark the end of word flag as false and delete the node if it ...read more

Find subset of numbers in array that sum up to zero.

• Use a nested loop to iterate through all possible subsets.

• Calculate the sum of each subset and check if it equals zero.

• Store the subset if the sum is zero.

• Optimize the solution by using a hash set to store the cumulative sum of elements.

BFS (Breadth-First Search) is a graph traversal algorithm that explores all the vertices of a graph in breadth-first order.

• BFS starts at a given vertex and explores all its neighbors before moving to the next level of vertices.

• It uses a queue data structure to keep track of the vertices to be visited.

• BFS guarantees that it visits all the vertices of a connected graph.

• It can be used to find the shortest path between two

In 5 years, I see myself as a highly skilled software developer, leading a team and contributing to innovative projects.

• Continuously improving my technical skills through learning and hands-on experience

• Taking on leadership roles and mentoring junior developers

• Contributing to the development of cutting-edge software solutions

• Building strong relationships with clients and stakeholders

• Staying updated with the latest indu...read more

My biggest achievement till date is successfully leading a team to develop and launch a new software product ahead of schedule.

• Led a team of developers to create a new software product

• Completed the project ahead of schedule

• Received positive feedback from clients and stakeholders

I would address conflicts directly and respectfully, seeking to understand the root cause and find a mutually beneficial solution.

• Listen actively to understand the other person's perspective

• Communicate clearly and respectfully

• Identify the root cause of the conflict

• Brainstorm potential solutions together

• Be willing to compromise and find a mutually beneficial solution

Success is achieving personal goals, feeling fulfilled, and making a positive impact.

• Success is subjective and can vary from person to person.

• It involves setting and achieving goals, both short-term and long-term.

• Feeling fulfilled and content with one's accomplishments is a key aspect of success.

• Making a positive impact on others or the world can also be a measure of success.

• Success is not just about material wealth or...read more

Dijkstra's algorithm finds the shortest path between nodes in a graph.

• Create a graph with nodes and edges

• Assign a tentative distance to each node

• Set the initial node as current and mark it visited

• For each neighbor of the current node, calculate the tentative distance

• If the tentative distance is less than the current distance, update the distance

• Mark the current node as visited and select the unvisited node with the sma...read more

A program to reverse a singly linked list

• Create a new empty linked list

• Traverse the original linked list and insert each node at the beginning of the new list

• Return the new list

Methods to find nth largest element in an unsorted linked list

• Traverse the linked list and store elements in an array, sort the array and return the nth largest element

• Use quickselect algorithm to find the nth largest element in O(n) time complexity

• Implement a max heap and extract the nth largest element

• Divide the linked list into smaller sublists and recursively find the nth largest element

• Use merge sort to sort the l

A prime number is a number that is divisible only by 1 and itself.

• A prime number has exactly two factors: 1 and itself.

• Prime numbers cannot be divided evenly by any other number.

• Examples of prime numbers include 2, 3, 5, 7, 11, 13, 17, etc.

Test cases for a bank transaction

• Transaction amount within account balance limit

• Transaction amount exceeds account balance limit

• Transaction to a valid account number

• Transaction to an invalid account number

• Transaction with correct transaction code

• Transaction with incorrect transaction code

• Transaction during bank working hours

• Transaction outside bank working hours

Design classes for educational institutions in a city

• Identify the main entities: schools, students, teachers, courses

• Create a School class with attributes like name, address, and a list of students and teachers

• Create a Student class with attributes like name, age, and a list of courses

• Create a Teacher class with attributes like name, specialization, and a list of courses

• Create a Course class with attributes like name, ...read more

Paypal is a leading online payment platform with a strong reputation and global presence.

• Paypal is a well-established and trusted online payment platform used by millions of users worldwide.

• It offers secure and convenient payment options for both individuals and businesses.

• Paypal has a strong focus on innovation and technology, making it an exciting place to work for software engineers.

• Working at Paypal provides opport...read more

Paypal is a digital payment platform that allows individuals and businesses to make online transactions.

• Paypal provides a secure way to send and receive money online.

• It allows users to link their bank accounts, credit cards, or debit cards to their Paypal account.

• Users can make payments to merchants or individuals using their Paypal balance or linked payment methods.

• Paypal offers buyer and seller protection, dispute re...read more

In 5 years, I see myself as a senior software engineer leading a team of developers on innovative projects.

• Continuing to enhance my technical skills and knowledge through ongoing learning and certifications

• Taking on more leadership responsibilities and mentoring junior team members

• Contributing to the development of cutting-edge software solutions

• Building strong relationships with colleagues and stakeholders to drive pr

Detecting loop in a linked list

• Use two pointers, one moving one node at a time and the other moving two nodes at a time

• If there is a loop, the two pointers will eventually meet

• If any of the pointers reach the end of the list, there is no loop

DFS (Depth-First Search) is a graph traversal algorithm that explores as far as possible along each branch before backtracking.

• DFS uses a stack to keep track of visited nodes and explore adjacent nodes.

• It can be implemented recursively or iteratively.

• DFS is useful for solving problems like finding connected components, detecting cycles, and solving mazes.

To find a cycle in a graph, use depth-first search (DFS) and keep track of visited nodes.

• Implement DFS algorithm to traverse the graph

• Maintain a visited array to keep track of visited nodes

• If a visited node is encountered again during DFS, a cycle exists

Hashing is a process of converting data into a fixed-size numerical value called a hash code.

• Hashing is used to quickly retrieve data from large datasets.

• It is commonly used in data structures like hash tables and hash maps.

• Hash functions should be fast, deterministic, and produce unique hash codes for different inputs.

• Examples of hash functions include MD5, SHA-1, and SHA-256.

The question asks for the number of pairs between 1 and N that satisfy a specific mathematical relation.

• The relation is pow(a,3) + pow(b,3) = pow(c,3) + pow(d,3)

• The values of a, b, c, and d should be less than or equal to N

• Count the number of pairs that satisfy the relation

Merge sort is a divide-and-conquer algorithm that recursively divides an array into two halves, sorts them, and then merges them.

• Divide the array into two halves

• Recursively sort each half

• Merge the sorted halves back together

• Repeat until the entire array is sorted

I want to join PayPal because of its innovative technology, global impact, and strong company culture.

• Innovative technology - PayPal is known for its cutting-edge technology and digital payment solutions.

• Global impact - Working at PayPal would allow me to contribute to a company that has a worldwide reach and influence.

• Strong company culture - I value a company that prioritizes diversity, inclusion, and employee well-b...read more

I recently learned about the benefits of using Docker for containerization.

• Docker allows for easy packaging and deployment of applications

• It helps in creating consistent environments across different platforms

• Docker containers are lightweight and efficient

• Example: I used Docker to containerize a microservices architecture for a recent project