eVanik Software Developer Interview Questions and Answers

Round duration - 90 minutes
Round difficulty - Easy

This was MCQ+Coding round.

Q1. How can you check if two strings are anagrams of each other?
Ans. 
Check if two strings are anagrams by comparing the sorted versions of the strings.
• Sort both strings and compare if they are equal.

• Use a hashmap to store the frequency of characters in each string and compare the maps.

• Ignore spaces and punctuation when comparing the strings.
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Round duration - 90 minutes
Round difficulty - Easy

This was face to face interview round.

Round duration - 90 minutes
Round difficulty - Easy

This was face to face interview round.

Round duration - 90 Minutes
Round difficulty - Medium

Interview started at 11:00 am. It was an online round. During the coding round I submitted optimized solution and got full acceptance of the solutions.

Q1. 
Detect Cycle in a Directed Graph
You are provided with a directed graph composed of 'N' nodes. You have a matrix called 'EDGES' with dimensions M x 2, which specifies the 'M' edges in the graph. Each edge...read more
Ans. 
Detect cycle in a directed graph using depth-first search (DFS) algorithm.
• Use DFS to traverse the graph and detect back edges indicating a cycle.

• Maintain a visited array to keep track of visited nodes during traversal.

• If a node is visited again during traversal and it is not the parent node, then a cycle exists.

• Return true if a cycle is detected, false otherwise.
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Round duration - 80 Minutes
Round difficulty - Medium

Interview started at 10:00 am. Interview went well, I was able to connect with the interviewer and enjoyed the whole interview

Q1. 
Next Smallest Palindrome Problem Statement
Find the next smallest palindrome strictly greater than a given number 'N' represented as a string 'S'.
Explanation:
You are given a number in string format, a...read more
Ans. 
Find the next smallest palindrome greater than a given number represented as a string.
• Convert the string to an integer, find the next greater palindrome, and convert it back to a string.

• Handle cases where the number is a palindrome or has all digits as '9'.

• Consider both odd and even length numbers when finding the next palindrome.
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Round duration - 80 Minutes
Round difficulty - Medium

Interview started at 11:00 am. Interview went well.

Q1. 
Boundary Traversal of a Binary Tree
Given a binary tree of integers, your task is to return the boundary nodes of the tree in Anti-Clockwise direction starting from the root node.
Input:
The first line ...read more
Ans. 
Return the boundary nodes of a binary tree in Anti-Clockwise direction starting from the root node.
• Traverse the left boundary nodes in a top-down manner

• Traverse the leaf nodes from left to right

• Traverse the right boundary nodes in a bottom-up manner

• Handle cases where duplicates occur in the boundary nodes

• Implement the function without printing as printing is already managed
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Round duration - 120 minutes
Round difficulty - Medium

Evening test around 5
Platform :- SHL
Environment was amazing

Q1. 
Subtree of Another Tree Problem Statement
Given two binary trees, T and S, determine whether S is a subtree of T. The tree S should have the same structure and node values as a subtree of T.
Explanation:
...read more
Ans. 
Given two binary trees T and S, determine if S is a subtree of T with the same structure and node values.
• Check if the second tree is a subtree of the first tree by comparing their structures and node values.

• Use a recursive approach to traverse both trees and check for equality.

• Handle cases where one tree is null or the values do not match.

• Return true if S is a subtree of T, false otherwise.
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Q2. 
Search in a Row-wise and Column-wise Sorted Matrix Problem Statement
You are given an N * N matrix of integers where each row and each column is sorted in increasing order. Your task is to find the positi...read more
Ans. 
Given a sorted N*N matrix, find the position of a target integer X.
• Iterate over each row and column to find the target integer X

• Utilize the sorted nature of the matrix to optimize the search process

• Return the position of X if found, else return -1 -1
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Round duration - 60 minutes
Round difficulty - Medium

1 Hour 
Afternoon

Q1. 
Intersection of Linked List Problem
You are provided with two singly linked lists containing integers, where both lists converge at some node belonging to a third linked list.
Your task is to determine t...read more
Ans. 
Find the node where two linked lists merge, return -1 if no merging occurs.
• Traverse both lists to find their lengths and the difference in lengths

• Move the pointer of the longer list by the difference in lengths

• Traverse both lists simultaneously until they meet at the merging point
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Q2. 
Problem: Pair Sum in a Binary Search Tree
Given a Binary Search Tree (BST) and an integer 'S', your task is to find all pairs of nodes within the BST that total to 'S' and return these pairs. If no such p...read more
Ans. 
Find pairs of nodes in a BST that sum up to a given value 'S'.
• Traverse the BST in-order to get a sorted list of nodes.

• Use two pointers approach to find pairs with sum 'S'.

• Keep track of visited nodes to avoid using the same node twice in a pair.
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Round duration - 60 minutes
Round difficulty - Medium

Online Round held on Chime

Q1. 
Is Binary Heap Tree Problem Statement
You are given a binary tree of integers. Your task is to determine if it is a binary heap tree or not.
Input:
The first line of input contains an integer ‘T’ denoti...read more
Ans. 
Determine if a given binary tree is a binary heap tree or not based on certain properties.
• Check if the binary tree is a complete binary tree where every level, except the last level, is completely filled and the last level is as far left as possible.

• Ensure that every parent node is greater than all its children nodes, forming a max-heap.

• If any node does not have a left or right child, it should be represented as -1 in
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Q2. 
Edit Distance Problem Statement
Given two strings S and T with lengths N and M respectively, your task is to find the "Edit Distance" between these strings.
The Edit Distance is defined as the minimum nu...read more
Ans. 
The task is to find the minimum number of operations required to convert one string into another using delete, replace, and insert operations.
• Use dynamic programming to solve the problem efficiently.

• Create a 2D array to store the edit distances between substrings of the two input strings.

• Fill up the array based on the minimum of three possible operations: insert, delete, or replace.

• The final answer will be the value at...read more
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Round duration - 90 Minutes
Round difficulty - Medium

This is a written round on paper for everyone. Three coding questions were given. Two out of three must be correct covering every single edge case to qualify for the next round. Only the most optimal solution was to be considered.

Q1. 
Maximum Subarray Sum Problem Statement
Given an array ARR consisting of N integers, your goal is to determine the maximum possible sum of a non-empty contiguous subarray within this array.
Example of Sub...read more
Ans. 
Find the maximum sum of a contiguous subarray in an array of integers.
• Use Kadane's algorithm to find the maximum subarray sum in linear time.

• Initialize two variables: maxSum and currentSum.

• Iterate through the array and update currentSum by adding the current element or starting a new subarray.

• Update maxSum if currentSum becomes greater than maxSum.

• Return maxSum as the maximum subarray sum.
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Round duration - 50 Minutes
Round difficulty - Easy

This was face to face interview round.

Q1. 
Finding Triplets in a Binary Tree Problem Statement
You are given a Binary Tree of integers and an integer 'X'. Your task is to find all the triplets in the tree whose sum is strictly greater than 'X'. Th...read more
Ans. 
Find all triplets in a binary tree whose sum is greater than a given integer X, with a grandparent-parent-child relationship.
• Traverse the binary tree to find all possible triplets.

• Check if the sum of each triplet is greater than X.

• Ensure the relationship of grandparent-parent-child in each triplet.

• Return the valid triplets in any order.

• Handle constraints and edge cases appropriately.
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Round duration - 60 Minutes
Round difficulty - Easy

FACE TO FACE ROUND INTERVIEW

Q1. Can you tell me about yourself?
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Q2. What is the difference between Mutex and Semaphores? Please provide a real-life example.
Ans. 
Mutex is used for exclusive access to a resource by only one thread at a time, while Semaphores can allow multiple threads to access a resource simultaneously.
• Mutex is binary and allows only one thread to access a resource at a time, while Semaphores can have a count greater than one.

• Mutex is used for protecting critical sections of code, while Semaphores can be used for controlling access to a pool of resources.

• Exampl...read more
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Round duration - 25 Minutes
Round difficulty - Medium

Very friendly interviewer. Although waiting time was very high

Q1. 
Pair Sum Problem Statement
You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to find and return a list of all pairs of elements where each sum of a pair equals 'S'.
Note:
...read more
Ans. 
Find pairs of elements in an array that sum up to a given value, sorted in a specific order.
• Iterate through the array and for each element, check if the complement (S - current element) exists in a hash set.

• If the complement exists, add the pair to the result list.

• Sort the result list based on the criteria mentioned in the question.

• Return the sorted list of pairs.
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Round duration - 90 minutes
Round difficulty - Medium

 Around 65-70 people sat for the test. 15 people were shortlisted. It consisted of the following to be done in 90 minutes.

- 28 MCQs based on core CS 

- 2 Coding questions – everyone had different and random questions. Most questions were custom logic based (easy level) including some standard questions – LCS, LIS, topological sort.

Round duration - 60 minutes
Round difficulty - Easy

Interviewer was very friendly. It started with the standard – tell me about yourself / introduce yourself type of question. Then he proceeded and asked two coding questions

Q1. 
Remove Duplicates from a Sorted Linked List
Your friend has homework to complete. Help him by removing duplicates from a sorted linked list.
You are given the 'Head' of a sorted linked list. Modify the l...read more
Ans. 
Remove duplicates from a sorted linked list without adjacent duplicates.
• Traverse the linked list while comparing current and next nodes.

• If they are equal, skip the next node by updating the current node's next pointer.

• Repeat until the end of the list is reached.
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Q2. 
Course Schedule Problem Statement
You are enrolled as a student and must complete N courses, numbered from 1 to N, to earn your degree.
Some courses have prerequisites, which means that to take course i,...read more
Ans. 
Check if it is feasible to complete all courses with prerequisites.
• Create a graph representing the prerequisites with courses as nodes and edges as prerequisites.

• Perform a topological sort on the graph to check if there is a cycle (if there is, then it's not feasible to complete all courses).

• If there is no cycle, then it is feasible to complete all courses.
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Round duration - 60 minutes
Round difficulty - Medium

This round had only 1 question. The interviewer introduced himself. And he advised me to clearly understand the problem before proceeding.

Q1. 
LCA of Binary Tree Problem Statement
You are given a binary tree of distinct integers, along with two nodes, ‘X’ and ‘Y’. Your task is to determine the Lowest Common Ancestor (LCA) of ‘X’ and ‘Y’.
The LC...read more
Ans. 
Find the Lowest Common Ancestor of two nodes in a binary tree.
• Traverse the binary tree to find the paths from the root to nodes X and Y.

• Compare the paths to find the last common node, which is the Lowest Common Ancestor.

• Implement a recursive function to efficiently find the LCA.

• Handle cases where one node is an ancestor of the other.

• Consider edge cases like when X or Y is the root node.
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Round duration - 60 minutes
Round difficulty - Medium

Pretty Good Round. Fast Paced. We covered a lot of ground.

Q1. 
Binary Search Tree Iterator Problem Statement
Design and implement a class BSTIterator to perform an in-order traversal over a Binary Search Tree (BST). Your implementation should include the following me...read more
Ans. 
Design and implement a class BSTIterator to perform in-order traversal over a Binary Search Tree (BST).
• Implement a parameterized constructor to initialize the iterator with the root of the BST.

• Implement a method 'next()' to return the next smallest element in in-order traversal.

• Implement a method 'hasNext()' to check if there exists a next smallest element in traversal.

• Ensure the output is the in-order traversal of the
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Q2. 
Maximum Consecutive Ones Problem Statement
Given a binary array 'ARR' of size 'N', your task is to determine the maximum length of a sequence consisting solely of 1’s that can be obtained by converting at...read more
Ans. 
Find the maximum length of a sequence of 1's by converting at most K zeroes into ones in a binary array.
• Iterate through the array and keep track of the current window of 1's and zeroes.

• Use a sliding window approach to find the maximum length of consecutive 1's by flipping at most K zeroes.

• Update the window based on the number of zeroes flipped and keep track of the maximum length found so far.

• Return the maximum length ...read more
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Q3. 
BFS in Graph Problem Statement
You are given an undirected and disconnected graph G(V, E) having V vertices numbered from 0 to V-1 and E edges. Your task is to print its BFS traversal starting from the 0t...read more
Ans. 
BFS traversal of an undirected and disconnected graph starting from vertex 0.
• Start BFS traversal from vertex 0 and visit all connected nodes in sorted order.

• Use a queue to keep track of nodes to visit next.

• Keep a visited array to avoid revisiting nodes.

• Print the BFS traversal path as the nodes are visited.

• Example: For input V=5, E=4 and edges 0-1, 0-2, 1-3, 2-4, the BFS traversal will be [0, 1, 2, 3, 4].
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Q4. 
Dijkstra's Shortest Path Problem Statement
Given an undirected graph with V vertices (labeled 0, 1, ..., V-1) and E edges, each edge connects two nodes X and Y with a specified weight representing the dis...read more
Ans. 
Dijkstra's algorithm is used to find the shortest path distance from a source node to all other nodes in an undirected graph.
• Implement Dijkstra's algorithm to find the shortest path distance from node 0 to all other nodes in the graph.

• Use a priority queue to efficiently select the next node with the shortest distance.

• Initialize distances to all nodes as infinity, except for the source node which is 0.

• Update distances t...read more
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Round duration - 60 minutes
Round difficulty - Hard

Bar Raised Round. Definitely felt the difficulty.

Q1. 
First Non-Repeating Character Problem Statement
You are given a string consisting of English alphabet characters. Your task is to identify and return the first character in the string that does not repeat...read more
Ans. 
Identify and return the first non-repeating character in a string, or the first character if all characters repeat.
• Iterate through the string to count the frequency of each character

• Iterate through the string again to find the first character with frequency 1

• If no such character is found, return the first character of the string
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