Elgi Ultra Industries Interview Questions and Answers for Freshers

Round duration - 180 Minutes
Round difficulty - Medium

Round was held in the morning at 10 am.

Q1. 
M - Coloring Problem Statement
Given an undirected graph with 'N' nodes in the form of an adjacency matrix and an integer 'M', determine if it is possible to color the vertices of the graph using at most ...read more
Ans. 
The problem involves determining if a given graph can be colored with at most 'M' colors without adjacent vertices sharing the same color.
• Create a function that takes the adjacency matrix, number of nodes 'N', and maximum number of colors 'M' as input.

• Implement a graph coloring algorithm such as backtracking or greedy coloring to check if the graph can be colored with at most 'M' colors.

• Check if adjacent vertices have ...read more
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Round duration - 40 Minutes
Round difficulty - Medium

The round was held in the evening

Q1. 
Trie Data Structure Implementation
Design and implement a Trie (prefix tree) to perform the following operations:
• insert(word): Add a string "word" to the Trie.
• search(word): Verify if the string "w...read more
Ans. 
Implement a Trie data structure to insert, search, and check for prefixes in strings.
• Create a TrieNode class with children and isEndOfWord attributes.

• Implement insert, search, and startsWith methods in the Trie class.

• Use a Trie to efficiently store and search for strings based on prefixes.

• Example: insert 'apple', search 'apple' returns true, startsWith 'app' returns true, search 'app' returns false.
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Round duration - 10 Minutes
Round difficulty - Easy

Was held in the morning around 9 am

Round duration - 120 Minutes
Round difficulty - Medium

The round had 2 coding problems to solve with varying difficulty. Each candidate had a different set of questions. The round was around 2 pm. The webcam was turned on to keep an eye on candidates.

Q1. 
Bursting Balloons Problem
Given an array ARR of size N, where each element represents the height of a balloon. The task is to destroy all balloons by shooting arrows from left to right. When an arrow hits...read more
Ans. 
Find the minimum number of arrows needed to burst all balloons by shooting arrows from left to right.
• Sort the array in non-decreasing order to make it easier to calculate the minimum number of arrows needed.

• Iterate through the sorted array and count the number of times the height decreases compared to the previous balloon.

• The count of decreases + 1 will give the minimum number of arrows needed to burst all balloons.

• Exa...read more
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Q2. 
Count Leaf Nodes in a Binary Tree
Count the number of leaf nodes present in a given binary tree. A binary tree is a data structure where each node has at most two children, known as the left child and the...read more
Ans. 
Count the number of leaf nodes in a binary tree.
• Traverse the binary tree and check if both left and right children are NULL to identify leaf nodes.

• Use recursion to traverse the tree efficiently.

• Keep track of the count of leaf nodes as you traverse the tree.

• Handle base cases where the current node is NULL or a leaf node.
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 questions related to DSA. I was first asked to explain my approach with proper complexity analysis and then code the soution in any IDE that I prefer.

Q1. 
Rod Cutting Problem Statement
Given a rod of a certain length, the rod can be divided into different sizes, each with an associated cost. Your task is to determine the maximum cost that can be obtained by...read more
Ans. 
The Rod Cutting Problem involves maximizing the profit obtained by cutting a rod into smaller pieces and selling them.
• Use dynamic programming to solve this problem efficiently.

• Create a table to store the maximum profit for each sub-length of the rod.

• Iterate through the rod lengths and update the table with the maximum profit.

• The final answer will be the maximum profit for the total length of the rod.
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Q2. 
Count Subarrays with Given XOR Problem Statement
You are given an array of integers ARR and an integer X. Your task is to determine the number of subarrays of ARR whose bitwise XOR is equal to X.
Example...read more
Ans. 
Count the number of subarrays in an array whose XOR is equal to a given value.
• Iterate through the array and keep track of XOR values and their frequencies using a hashmap.

• For each element in the array, calculate the XOR with the current element and check if the required XOR value exists in the hashmap.

• Increment the count of subarrays whenever the required XOR value is found in the hashmap.
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 questions of DSA of Easy-Medium difficulty and at the end I was asked a Puzzle to check my general problem solving ability.

Q1. 
Rotting Oranges Problem Statement
You are given a grid containing oranges where each cell of the grid can contain one of the three integer values:
• 0 - representing an empty cell
• 1 - representing a fre...read more
Ans. 
Find the minimum time required to rot all fresh oranges in a grid.
• Use Breadth First Search (BFS) to simulate the rotting process of oranges.

• Keep track of the time taken to rot all oranges and the count of fresh oranges remaining.

• If all fresh oranges are not rotten after simulation, return -1.

• Handle edge cases like empty grid or no fresh oranges present.

• Example: For the given grid, the minimum time required is 4 seconds...read more
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Q2. 
Detect and Remove Loop in Linked List
For a given singly linked list, identify if a loop exists and remove it, adjusting the linked list in place. Return the modified linked list.
Expected Complexity:
A...read more
Ans. 
Detect and remove loop in a singly linked list in place with O(n) time complexity and O(1) space complexity.
• Use Floyd's Cycle Detection Algorithm to identify the loop in the linked list.

• Once the loop is detected, use two pointers approach to find the start of the loop.

• Adjust the pointers to remove the loop and return the modified linked list.

• Example: For input 5 2 and 1 2 3 4 5, return 1 2 3 4 5 without the loop.
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Q3. You have two wires of different lengths that are both capable of burning for exactly one hour when ignited at both ends. How can you measure a time interval of 45 minutes using these two wires?
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Round duration - 50 Minutes
Round difficulty - Medium

This round had 2 Algorithmic questions wherein I was supposed to code both the problems after discussing their
approaches and respective time and space complexities . After that , I was grilled on some OOPS concepts related to C++.

Q1. 
Longest Palindromic Substring Problem Statement
You are provided with a string STR of length N. The task is to find the longest palindromic substring within STR. If there are several palindromic substring...read more
Ans. 
Given a string, find the longest palindromic substring within it.
• Iterate through the string and expand around each character to find palindromes

• Keep track of the longest palindrome found so far

• Return the longest palindromic substring
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Q2. 
Quick Sort Problem Statement
You are provided with an array of integers. The task is to sort the array in ascending order using the quick sort algorithm.
Quick sort is a divide-and-conquer algorithm. It ...read more
Ans. 
Yes, the quick sort algorithm can be enhanced to achieve NlogN complexity in the worst case by using a randomized version of the algorithm.
• Randomized quick sort involves randomly selecting the pivot element to reduce the chances of worst-case scenarios.

• By choosing a random pivot, the algorithm becomes less predictable and more likely to achieve the desired time complexity.

• This enhancement helps in avoiding the worst-ca...read more
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Q3. What are friend functions in C++?
Ans. 
Friend functions in C++ are functions that are not members of a class but have access to its private and protected members.
• Friend functions are declared inside a class with the keyword 'friend'.

• They can access private and protected members of the class.

• They are not member functions of the class, but have the same access rights as member functions.

• Friend functions are useful for implementing operators that are not part ...read more
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Q4. What is the difference between Early Binding and Late Binding in C++?
Ans. 
Early binding is resolved at compile time while late binding is resolved at runtime in C++.
• Early binding is also known as static binding, where the function call is resolved at compile time based on the type of the object.

• Late binding is also known as dynamic binding, where the function call is resolved at runtime based on the actual type of the object.

• Early binding is faster as the function call is directly linked to ...read more
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Round duration - 60 minutes
Round difficulty - Easy

This was coding round and was conducted on Cocubes platform. It is not IDE but kind of white board coding platform. C/C++, Java and Python were only allowed languages.

Round duration - 30 minutes
Round difficulty - Easy

This was pen and paper round. Total 40 shortlisted candidates were grouped into 8 groups (each of 5). Each group was given a coding question which they have to solve on paper and explain it to the recruiter. 2 to 3 from each group were selected for the next round.

Round duration - 60 minutes
Round difficulty - Easy

This was general face to face Data Structures and Algorithms based round.

Q1. How do you perform a spiral order traversal of a binary tree? Please provide an explanation or code to print the binary tree in spiral order.
Ans. 
Spiral order traversal of a binary tree involves printing nodes level by level alternating between left to right and right to left.
• Start by pushing the root node into a queue.

• While the queue is not empty, pop a node, print its value, and push its children into the queue.

• For each level, alternate between printing nodes from left to right and right to left.

• Repeat until all nodes are printed in spiral order.
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Round duration - 45 minutes
Round difficulty - Easy

It was the last round.

About my ...CV and my approch to this company

Round duration - 40 minutes
Round difficulty - Medium

It was conducted on hackkerank. MCQs cover various topics including -Data Structures, Aptitude, etc

Q1. 
Count Diagonal Paths
You are given a binary tree. Your task is to return the count of the diagonal paths to the leaf of the given binary tree such that all the values of the nodes on the diagonal are equa...read more
Ans. 
Count the number of diagonal paths in a binary tree where all nodes on the diagonal have equal values.
• Traverse the binary tree in a diagonal manner and keep track of nodes with equal values.

• Use recursion to explore all possible diagonal paths in the tree.

• Count the number of paths where all nodes on the diagonal have the same value.
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Round duration - 20 minutes
Round difficulty - Medium

This round was conducted on skype. Questions were mainly personality based rather knowledge.

Round duration - 180 minutes
Round difficulty - Easy

This was Online Coding round on Samsung Software. There were 50 test cases and all test cases should be passed to get selected.

Round duration - 30 minutes
Round difficulty - Easy

This was also Face to Face coding Interview totally based on Data Structures and Algorithms.

Q1. The Longest Increasing Subsequence (LIS) problem is to find the length of the longest subsequence of a given sequence such that all elements of the subsequence are sorted in increasing order.
Ans. 
The Longest Increasing Subsequence (LIS) problem is to find the length of the longest subsequence of a given sequence with increasing order.
• Use dynamic programming to solve the LIS problem efficiently.

• Maintain an array to store the length of the LIS ending at each element.

• Iterate through the array and update the LIS length based on previous elements.

• Example: For input [10, 22, 9, 33, 21, 50, 41, 60, 80], the LIS is [10...read more
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Round duration - 30 minutes
Round difficulty - Easy

This Face to Face Interview was Based on coding and projects.

Q1. Implement the Depth First Search (DFS) algorithm for a graph.
Ans. 
DFS is a graph traversal algorithm that explores as far as possible along each branch before backtracking.
• Start at a node and explore as far as possible along each branch before backtracking

• Use a stack to keep track of nodes to visit

• Mark visited nodes to avoid revisiting them

• Recursive implementation is common
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Round duration - 15 minutes
Round difficulty - Easy

HR round was mainly based on questions about myself and my knowledge about the company.

Q1. Tell me about yourself and your family background.
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Round duration - 180 minutes
Round difficulty - Easy

1) 1 coding question need to be solved in 3 hours.there will be 50 test cases, need to pass all the test cases to go to the next rounds.STL in c++ cannot be used, we need to code anything we use from scratch

2) Coding questions will mainly be based on dynamic programming, graphs and backtracking, so prepare those topics well.

Q1. 
Rat in a Maze Problem Statement
You need to determine all possible paths for a rat starting at position (0, 0) in a square maze to reach its destination at (N-1, N-1). The maze is represented as an N*N ma...read more
Ans. 
Find all possible paths for a rat in a maze from source to destination.
• Use backtracking to explore all possible paths in the maze.

• Keep track of visited cells to avoid revisiting them.

• Explore all possible directions ('U', 'D', 'L', 'R') from each cell.

• Return the list of valid paths sorted in alphabetical order.
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Round duration - 60 minutes
Round difficulty - Medium

The technical interview 1 has some questions based on basics of oops, Os and one/two coding questions.
Students who clear this round have to go for another technical round

Q1. 
Reverse Linked List Problem Statement
Given a singly linked list of integers, return the head of the reversed linked list.
Example:
Initial linked list: 1 -> 2 -> 3 -> 4 -> NULL
Reversed link...read more
Ans. 
Reverse a singly linked list of integers and return the head of the reversed linked list.
• Iterate through the linked list and reverse the pointers to point to the previous node.

• Use three pointers - prev, current, and next to reverse the linked list in O(N) time and O(1) space complexity.

• Update the head of the reversed linked list as the last node encountered during reversal.
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Q2. 
Delete a Given Node from Doubly Linked List
Ninja is learning about doubly linked lists and wants to remove a specified element from the list. Can you assist Ninja in doing this and returning the modified...read more
Ans. 
Remove a specified element from a doubly linked list and return the modified list.
• Traverse the doubly linked list to find the specified element to be removed.

• Update the pointers of the previous and next nodes to skip the node to be deleted.

• Handle edge cases like removing the head or tail of the linked list.

• Return the modified linked list after removing the specified element.
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Round duration - 60 Minutes
Round difficulty - Easy

The interview again began with my resume but it was very exhaustive. While my friends were asked about both resume and DSA concepts, my interview focused entirely on my resume. I had done a project on distributed computing and the interviewer asked me an application question on multi-threading and synchronisation. It was quite difficult because I was trying to explain my approach and I couldn’t make out if the interviewer was happy with my approach or not. Then he asked to design a contact database without the actual use of DBMS in java. Again I tried to explain my approach but it was tough. The interview ended after asing one or more coding questions.

Q1. 
Spiral Order Traversal of a Binary Tree
Given a binary tree with N nodes, your task is to output the Spiral Order traversal of the binary tree.
Input:
The input consists of a single line containing elem...read more
Ans. 
Implement a function to return the spiral order traversal of a binary tree.
• Traverse the binary tree level by level, alternating between left to right and right to left.

• Use a queue to keep track of nodes at each level.

• Append nodes to the result list in the order they are visited.

• Handle null nodes appropriately to maintain the spiral order.

• Example: For input 1 2 3 -1 -1 4 5, the output should be 1 3 2 4 5.
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Q2. 
Cycle Detection in a Singly Linked List
Determine if a given singly linked list of integers forms a cycle or not.
A cycle in a linked list occurs when a node's next points back to a previous node in the ...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.
• Use Floyd's Cycle Detection Algorithm to determine if there is a cycle in the linked list.

• Maintain two pointers, one moving at twice the speed of the other, if they meet at any point, there is a cycle.

• Check if the next pointer of any node points to a previously visited node to detect a cycle.
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Round duration - 30 minutes
Round difficulty - Easy

This was about 30 minutes long interview. First, she asked introduction, after that she was very interested in my internship that I did in summer and about my interests. She asked few common questions on that.