Droisys Senior QA Engineer 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

Use bitwise operations to find the sum of two numbers without using mathematical operators.

• Use bitwise XOR to find the sum of two numbers without carrying.

• Use bitwise AND and left shift to find the carry.

• Repeat the process until there is no carry left.

To delete a node from a linked list when only given a reference to the node, we can copy the data of the next node to the given node and delete the next node.

• Copy the data of the next node to the given node

• Update the next pointer of the given node to skip the next node

• Delete the next node

The question asks to fill the blanks in a pyramid where each number is the sum of the numbers in the bottom two cells.

• Start from the bottom row and work your way up, calculating the sum of the numbers in the bottom two cells for each blank space.

• Use a loop to iterate through each row and column of the pyramid.

• Store the calculated sum in the corresponding blank space.

• Repeat the process until all the blanks are filled.

Moore's Law is the observation that the number of transistors in a dense integrated circuit doubles about every two years.

• Named after Intel co-founder Gordon Moore

• First stated in 1965

• Has been a driving force behind technological advancements

• Predicts exponential growth in computing power

• Has been challenged in recent years due to physical limitations

A process is an instance of a program while a thread is a subset of a process.

• A process has its own memory space while threads share memory space

• Processes are heavyweight while threads are lightweight

• Processes communicate through inter-process communication while threads communicate through shared memory

• Examples of processes include web browsers, text editors, etc. while examples of threads include GUI updates, backgro

Multi-core processors provide faster and more efficient computing.

• Improved performance and speed

• Ability to handle multiple tasks simultaneously

• Reduced power consumption

• Better multitasking capabilities

• Enhanced user experience

• Examples: Intel Core i7, AMD Ryzen 9

I am a software engineer with a loving family.

• I have been working as a software engineer for 5 years.

• My wife is a teacher and we have two children.

• We enjoy spending time together outdoors and traveling.

• My parents live in a different state but we keep in touch regularly.

• Family is very important to me and I prioritize spending time with them.

Developed a web-based project management tool and a mobile app for tracking expenses

• Created a responsive UI using React and Bootstrap

• Implemented user authentication and authorization using Firebase

• Integrated Google Maps API for location tracking in the mobile app

• Used Node.js and MongoDB for backend development

• Collaborated with a team of four to complete the projects

I have 5 years of experience in software engineering with expertise in Java and Python.

• Developed and maintained web applications using Java and Spring framework

• Designed and implemented RESTful APIs using Python and Flask

• Worked on database management and optimization using MySQL and MongoDB

• Collaborated with cross-functional teams to deliver high-quality software products

• Participated in code reviews and provided construc

My academic interests include computer science, artificial intelligence, and machine learning.

• Computer science

• Artificial intelligence

• Machine learning

Explain Big O notation

• Big O notation is used to describe the time complexity of an algorithm

• It helps us understand how the algorithm's performance changes with input size

• O(1) means constant time, O(n) means linear time, O(n^2) means quadratic time

• We want algorithms with lower Big O values for better performance

I am open to relocation based on the job opportunity and growth prospects.

• Open to relocation for the right opportunity

• Willing to move for career growth

• Flexible with location based on job requirements

Yes, I would love to have a pizza slice!

• I am a big fan of pizza and would never say no to a slice!

• Pizza is the perfect food for any occasion, whether it's a quick lunch or a late-night snack.

• I particularly enjoy pepperoni and mushroom pizza, but I'm open to trying new toppings as well.