CodeNation SDE (Software Development Engineer) Interview Questions and Answers

Round duration - One hour aptitude,1.5 hour coding
Round difficulty - Medium

First round was of aptitude that was easy and second round was of coding which had medium level questions.

Q1. 
Prime Numbers Identification
Given a positive integer N, your task is to identify all prime numbers less than or equal to N.
Explanation:
A prime number is a natural number greater than 1 that has no po...read more
Ans. 
Identify all prime numbers less than or equal to a given positive integer N.
• Iterate from 2 to N and check if each number is prime

• Use the Sieve of Eratosthenes algorithm for efficient prime number identification

• Optimize by only checking up to the square root of N for divisors
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Round duration - 20 minutes
Round difficulty - Medium

First I was asked about my projects and then 2 questions on array were given.

Q1. 
Count Pairs with Given Sum
Given an integer array/list arr and an integer 'Sum', determine the total number of unique pairs in the array whose elements sum up to the given 'Sum'.
Input:
The first line c...read more
Ans. 
Count the total number of unique pairs in an array whose elements sum up to a given value.
• Use a hashmap to store the frequency of each element in the array.

• Iterate through the array and for each element, check if (Sum - current element) exists in the hashmap.

• Increment the count of pairs if the complement exists in the hashmap.

• Divide the count by 2 to avoid counting duplicates (arr[i], arr[j]) and (arr[j], arr[i]) separ
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Round duration - 90 minutes
Round difficulty - Easy

First Round-It was 90 minutes round and basically contains aptitude question which you need to solve quickly.

Q1. MCQs
Normal aptitude and English and reasoning questions.
Ans. 
The question involves multiple choice questions on aptitude, English, and reasoning.
• Practice solving different types of aptitude questions like numerical reasoning, logical reasoning, and data interpretation.

• Improve your English skills by reading books, newspapers, and practicing grammar exercises.

• Enhance your reasoning abilities by solving puzzles, brain teasers, and logical reasoning problems.
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Round duration - 40 minutes
Round difficulty - Easy

My interview started and the interviewer asked me to introduce myself. Also he asked me some questions related to my hobbies like the last movie I saw in theatre (these questions are asked to make you comfortable and familiarise you with the interview) .

After this he asked me about my projects.
In which technology did I work. What is my project all about , what are its features and how is it useful in the real world.

After this, since I made my project in native Android using Java he asked me some conceptual questions in Java.He asked me about Collection framework.
After this he asked me about OOPs.What is OOPs, then he asked me about polymorphism and told me to explain it.

Finally, he gave me a question and asked me to code it.
Q. Find the second largest element in the given array (don't use sorting ).
Eg. arr={6,7,8,9,0}
Then, output=8

Interview took around 35-40 min .
At last he asked me if I had any questions for him to which I replied in what technologies do I get to work on if I get selected.

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 second largest element does not exist.
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It had mcq and 1 hard coding question

Q1. They asked me about backtracking and dp series problem and also to solve the given question
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Q2. Java and in depth about different pillars of java
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Easy to medium questions

Q1. Create a software
Ans. 
A software for managing inventory in a retail store
• Create a user-friendly interface for adding, updating, and deleting products

• Include features for tracking sales, restocking inventory, and generating reports

• Implement barcode scanning functionality for quick product lookup
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Q1. Tell me about yourself
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Fundamental output questions and aptitude assessments.

Q1. Pattern printing Delete drop truncate difference Projects discussion
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Q1. What motivated you to choose Dell?
Ans. 
I chose Dell for their reputation for innovation, strong company culture, and opportunities for growth.
• Reputation for innovation in technology industry

• Strong company culture focused on employee development

• Opportunities for growth and advancement within the company
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Q2. Opinion about JD.
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Round duration - 30 Minutes
Round difficulty - Easy

he interviews were conducted simultaneously for all on BlueJeans along with a code sharing website. After the initial set up and introduction, a set of 2 questions from DSA were asked from all candidates. The results were announced the same day.

Q1. 
DFS Traversal Problem Statement
Given an undirected and disconnected graph G(V, E), where V is the number of vertices and E is the number of edges, the connections between vertices are provided in the 'GR...read more
Ans. 
DFS traversal to find connected components in an undirected and disconnected graph.
• Use Depth First Search (DFS) algorithm to traverse the graph and find connected components.

• Maintain a visited array to keep track of visited vertices.

• For each unvisited vertex, perform DFS to explore all connected vertices and form a connected component.
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Q2. 
Median of Two Sorted Arrays
Given two sorted arrays A and B of sizes N and M, find the median of the merged array formed by combining arrays A and B. If the total number of elements, N + M, is even, the m...read more
Ans. 
Find the median of two sorted arrays by merging them and calculating the middle element(s).
• Merge the two sorted arrays into one sorted array.

• Calculate the median based on the total number of elements in the merged array.

• If the total number of elements is even, take the mean of the two middle elements as the median.
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Round duration - 120 mintues
Round difficulty - Medium

Aptitude round was in afternoon around 3 pm and every person who has given aptitude round was also given an other chance which was coding round. There was a time gap of 1 hr between two test. both of these went online. Environment was good without any lag. Webcam was on throughout the test. There were 3 coding questions, of which 2 were medium and one was easy. I attempted all of them.

Q1. 
String Rotation Problem Statement
You are given a string named str and an integer D. Your task is to perform both left (anticlockwise) and right (clockwise) rotations on the given string by D units, start...read more
Ans. 
Implement left and right string rotations by D units on a given string.
• Implement leftRotate() function to return string after left rotation by D units.

• Implement rightRotate() function to return string after right rotation by D units.

• Consider handling edge cases like empty string or D exceeding string length.

• Example: For input 'coding', D=2, leftRotate() should return 'dingco' and rightRotate() should return 'ngcodi'.
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Q2. 
Height of Binary Tree
You are provided with the Inorder and Level Order traversals of a Binary Tree composed of integers. Your goal is to determine the height of this Binary Tree without actually construc...read more
Ans. 
Calculate the height of a Binary Tree given its Inorder and Level Order traversals without constructing it.
• Use the properties of Inorder and Level Order traversals to determine the height of the Binary Tree.

• The height of a Binary Tree is the number of edges on the longest path from the root to a leaf node.

• Consider edge cases like a single node tree or empty tree when calculating the height.
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Q3. 
Common Elements Problem Statement
Identify and output the common strings present in both given arrays of lowercase alphabets for each test case.
Input:
The first line contains an integer 'T' representin...read more
Ans. 
The task is to find and output the common strings present in both given arrays of lowercase alphabets for each test case.
• Iterate through the elements of the second array and check if they are present in the first array.

• Use a hash set or map to efficiently check for common elements.

• Return the common strings in the order they appear in the second array.
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Round duration - 40 minutes
Round difficulty - Medium

This round was at 12 pm. Interviewer and I greeted each other and then he asked me to explain all the questions I had done during test. He shared screen with my report of test which was having the solutions I typed during coding rounds. It took around 20 minutes to explain all three questions. Interviewer was happy with my explanation. Then he had asked me one coding question and various questions based on my project. I answered him all with a smile.

Q1. 
Maximum Subarray Sum Problem Statement
Given an array arr of length N consisting of integers, find the sum of the subarray (including empty subarray) with the maximum sum among all subarrays.
Explanation...read more
Ans. 
Find the sum of the subarray with the maximum sum among all subarrays in an array of integers.
• Use Kadane's algorithm to find the maximum subarray sum efficiently.

• Initialize two variables, one for current sum and one for maximum sum.

• Iterate through the array and update the current sum and maximum sum accordingly.

• Return the maximum sum as the result.
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Round duration - 30 minutes
Round difficulty - Medium

It was in afternoon. HR called to me to fix a meeting on Microsoft teams. He was very polite with experience of corporate environment.