XpressBees Senior Software Tester Interview Questions and Answers

Find an odd occurring number among even occurring numbers.

• Use XOR operation to cancel out even occurring numbers and get the odd occurring number.

• Iterate through the array and XOR each element with the result variable.

• The final result will be the odd occurring number.

Print the spiral order of a binary tree and matrix.

• For binary tree, use level order traversal and alternate direction for each level.

• For matrix, use four pointers to traverse in spiral order.

• Example for binary tree: 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9

• Example for matrix: 1 2 3 4 -> 8 7 6 5 -> 9 10 11 12 -> 16 15 14 13

Finding pairs in an array with a given sum.

• Iterate through the array and for each element, check if the difference between the given sum and the element exists in the array.

• Use a hash table to store the elements of the array and their indices for faster lookup.

• If there are multiple pairs with the same sum, return any one of them.

• If no pair is found, return null or an empty array.

Find total number of k element with given avg in an array in minimum time complexity.

• Use sliding window technique to traverse the array in O(n) time complexity.

• Maintain a sum variable to keep track of the sum of elements in the window.

• If the sum of elements in the window is equal to k times the given avg, increment the count.

• Move the window by subtracting the first element and adding the next element in the array.

Printing non-boundary elements of a binary tree

• Traverse the tree in any order (preorder, inorder, postorder)

• Check if the current node is not a boundary node (not the first or last node in its level)

• If it is not a boundary node, print its value

• Recursively traverse its left and right subtrees

A generic swap function swaps two values of any data type.

• The function should take two parameters of any data type.

• Use a temporary variable to store the value of one parameter.

• Assign the value of the second parameter to the first parameter.

• Assign the value of the temporary variable to the second parameter.

Search for an element in a rotated sorted linked list.

• Find the pivot point where the list is rotated.

• Divide the list into two sublists based on the pivot point.

• Perform binary search on the appropriate sublist.

• Handle edge cases such as empty list and list with only one element.

Search an element in a rotated sorted array

• Find the pivot point where the array is rotated

• Divide the array into two sub-arrays based on pivot point

• Perform binary search on the appropriate sub-array

• Repeat until element is found or sub-array size is 1

Find 5 missing numbers in an array of size 95 containing numbers in range 1 to 100.

• Create a boolean array of size 100 and mark the present numbers

• Iterate through the boolean array and find the missing numbers

• Alternatively, use a HashSet to store the present numbers and find the missing ones

Given a Sudoku board, find possible numbers for an empty cell.

• Iterate through empty cells and check possible numbers using row, column, and box constraints.

• Use a set to keep track of possible numbers for each empty cell.

• Return the set of possible numbers for the given empty cell.

Find integer average of 4 unsigned integers without typecasting

• Add all the integers and divide by 4

• Use bit shifting to divide by 4

• Handle overflow by using long long data type

• Use unsigned int data type for input

Code to identify 32 bit or 64 bit architecture of a processor

• Check if the operating system is 32 bit or 64 bit

• If OS is 32 bit, processor is 32 bit

• If OS is 64 bit, check if processor supports 64 bit architecture

• Use CPUID instruction to check if processor supports 64 bit architecture

Convert binary number to base 64 integer

• Divide the binary number into groups of 6 bits

• Convert each group of 6 bits to decimal

• Map the decimal value to the corresponding base 64 character

• Concatenate the base 64 characters to form the final integer

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