ServiceNow Software Quality Engineer Interview Questions and Answers

Round duration - 120 minutes
Round difficulty - Easy

Type of Questions No. of Questions
Quantitative 20
Logical and Reasoning 20
Verbal 20
Section II: Coding Section
Number of Questions: 2
Time Duration: 60 min
Level of Difficulty: Easy-Medium
Type of Questions: String Manipulation and Tree based Question

Q1. 
Binary Tree Mirror Conversion Problem
Given a binary tree, your task is to convert it into its mirror tree.
A binary tree is a data structure where each parent node has at most two children.
The mirror ...read more
Ans. 
Convert a binary tree into its mirror tree by interchanging left and right children of non-leaf nodes.
• Traverse the binary tree in a recursive manner.

• Swap the left and right children of each non-leaf node.

• Continue this process until all nodes are visited.

• Output the inorder traversal of the mirror tree.
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Q2. 
Palindromic Partitioning Problem Statement
Given a string ‘str’, calculate the minimum number of partitions required to ensure every resulting substring is a palindrome.
Input:
The first line contains a...read more
Ans. 
The problem involves calculating the minimum number of partitions needed to ensure every resulting substring is a palindrome.
• Iterate through the string and check for palindromes at each possible partition point.

• Keep track of the minimum cuts needed to partition the string into palindromic substrings.

• Consider edge cases such as when the string is already a palindrome or when all characters are unique.

• Example: For input ...read more
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Round duration - 30 minutes
Round difficulty - Medium

It was a non eliminatory round comprising of 3 sections with a total time of 30 minutes.
Section I: Technical MCQ’s
Number of Questions: 20
Level of Difficulty: Medium -High
Programming Output questions and questions from CN, DBMS, OS and DS were asked.
Section II: Aptitude and Logical Section
Number of Questions: 10
Level of Difficulty: Easy
Section III: Coding Section
Number of Questions: 2
Level of Difficulty: Easy-Medium

Q1. 
Leaders in an Array Problem Statement
You are given a sequence of numbers. Your task is to find all leaders in this sequence. A leader is defined as an element that is strictly greater than all the elemen...read more
Ans. 
Find all leaders in a sequence - elements greater than all elements to their right.
• Iterate from right to left, keep track of maximum element encountered so far

• If current element is greater than maximum, it is a leader

• Return the leaders in the same order as the input sequence
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Q2. 
Spiral Matrix Path Problem
You are provided with a two-dimensional array named MATRIX of size N x M, consisting of integers. Your task is to return the elements of the matrix following a spiral order.
In...read more
Ans. 
Implement a function to return elements of a matrix in spiral order.
• Iterate through the matrix in a spiral order by adjusting the boundaries of rows and columns.

• Keep track of the direction of traversal (right, down, left, up) to properly move through the matrix.

• Handle edge cases such as when the matrix is empty or has only one row or column.
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Round duration - 80 minutes
Round difficulty - Medium

The interview went for about 75-80 minutes. I was not able to answer almost all the answers
correctly but gave almost 75% correct answers. The interviewer mainly focused on the problem
solving ability and the quality of conceptual knowledge.
1: Basic Introductory Questions
2: 2-3 Puzzle Questions 
3: Some basic Questions on DSA- about stacks, queue, arrays, memory storage accessing,
Advantages and Dis of Linked list over arrays,
4: Operating System: In all the rounds , Operating System questions were asked in abundance.
Though the questions were basic, they focused more on our concepts like how easily we were
able to explain it to them.
Questions on Kernels, Types of Kernel, Why OS, memory allocation in OS were asked.
5: Test Cases Question: We have to think and answer the possible questions while testing the
cases.
i: Test cases for a login page window.
6: Heavy discussions on the projects I have done. Why we preferred to use a particular
technology. What was my role in the project and so on.
7: I was asked to code some questions.

Q1. 
Find the Second Largest Element
Given an array or list of integers 'ARR', identify the second largest element in 'ARR'.
If a second largest element does not exist, return -1.
Example:
Input:
ARR = [2,...read more
Ans. 
Find the second largest element in an array of integers.
• Iterate through the array to find the largest and second largest elements.

• Handle cases where all elements are identical.

• Return -1 if a second largest element does not exist.
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Q2. 
Cycle Detection in a Linked List
Determine if a given Singly Linked List of integers forms a cycle.
Explanation:
A cycle exists in a linked list if a node's next pointer points back to a previous node, ...read more
Ans. 
Detect if a singly linked list forms a cycle by checking if a node's next pointer points back to a previous node.
• Traverse the linked list using two pointers, one moving at double the speed of the other.

• If the two pointers meet at any point, there is a cycle in the linked list.

• Use Floyd's Cycle Detection Algorithm for efficient detection.

• Example: Input: 3 2 0 -4 -1, 1 Output: true
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Round duration - 90 minutes
Round difficulty - Hard

This round of interview was took by a senior person of the company. It was a bit lengthy as we
had more of a discussion rather than just a QnA round. The interview went for more than 90
minutes and was tougher than the first round.
1: There was a long discussion on what I written in my resume. The projects I had done,
Extracurricular and co-curricular activities I had written on the resume, the skills I have
mentioned. All of it. So be careful of whatever you mention in the resume.
2: Next he asked me a bunch of coding questions which were some very popular ones
I was asked to code in my preferred language. So there wasn’t any language barrier and for all the
questions the interviewer asked for the most optimized approach.
As I was able to answer all the questions, I wasn’t asked any more questions.
3: After the coding questions, I was asked a lot of questions of Operation System and OOPS.
i: Fragmentation- Internal and External
ii: Concepts of Kernel
iii: File Management
iv: Virtual functions and Friend Functions
v: Function Overloading And Overriding
vi: What is paging and Demand Paging?
4: Interview puzzles:
5: Testing Based Questions-
i: Five new inventions in a glass frame and the test cases to test the working a frame.
ii: Design test cases for a shopping application.
The interviewer was quite satisfied with the test cases I answered. As the main trick to solve
these kind of interview questions is to design the test cases with giving every small function an
eye and then forming all possible scenarios for the same

Q1. 
Anagram Pairs Verification Problem
Your task is to determine if two given strings are anagrams of each other. Two strings are considered anagrams if you can rearrange the letters of one string to form the...read more
Ans. 
Check if two strings are anagrams of each other by comparing the sorted characters.
• Sort the characters of both strings and compare them.

• Use a dictionary to count the occurrences of characters in each string.

• Ensure both strings have the same length before proceeding.

• Handle edge cases like empty strings or strings with different lengths.

• Example: str1 = 'listen', str2 = 'silent' should return True.
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Q2. 
Find K'th Character of Decrypted String
You are given an encrypted string where repeated substrings are represented by the substring followed by its count. Your task is to find the K'th character of the d...read more
Ans. 
Given an encrypted string with repeated substrings represented by counts, find the K'th character of the decrypted string.
• Parse the encrypted string to extract substrings and their counts

• Iterate through the decrypted string to find the K'th character

• Handle cases where counts are more than one digit or in parts
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Q3. 
Queue Using Stacks Problem Statement
Implement a queue data structure which adheres to the FIFO (First In First Out) principle, utilizing only stack data structures.
Explanation:
Complete predefined fun...read more
Ans. 
Implement a queue using only stack data structures, supporting FIFO principle.
• Use two stacks to simulate a queue: one for enqueueing and one for dequeueing.

• For enQueue operation, push elements onto the enqueue stack.

• For deQueue operation, if dequeue stack is empty, transfer elements from enqueue stack.

• For peek operation, return top element of dequeue stack.

• For isEmpty operation, check if both stacks are empty.
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Q4. 
Stack using Two Queues Problem Statement
Develop a Stack Data Structure to store integer values using two Queues internally.
Your stack implementation should provide these public functions:
Explanation:
...read more
Ans. 
Implement a stack using two queues to store integer values with specified functions.
• Create a stack class with two queue data members.

• Implement push, pop, top, size, and isEmpty functions.

• Ensure proper handling of edge cases like empty stack.

• Use queue operations like enqueue and dequeue to simulate stack behavior.

• Maintain the size of the stack and check for emptiness.

• Example: Push 42, pop to get 42, push 17, top to get
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Round duration - 70 minutes
Round difficulty - Easy

This was also similar to the last two Technical Interviews and was also easier from them. The
interview went for about 70 minutes and it was tilted more towards managerial side and less
technical questions were asked.
1. Program to Count set nits in an integer. (I answered 4 possible solutions to him and he was
satisfied) 
2: Working of Bubble Sort and Insertion Sort ( I was asked to dry run the solution mainly to
check the internal working of swapping and comparison)
3: Some Mathematical Puzzles
4: Design test cases for OLA Application
5: Design test cases for GMAIL Application
6: Situation based questions

Round duration - 15 minutes
Round difficulty - Easy

It was the last round and an eliminatory round as well. It was a 15 minutes long discussion round
about college life, interests, and hobbies. The HR also asked our preferred joining location
between Noida and Bangalore which gave us many hopes of our selection.
Three candidates from our college went till the HR Round.