Crest Infosystems Web Developer Interview Questions and Answers

Q1. Create a Todo app
Ans. 
A simple Todo app to manage tasks and deadlines
• Create a form to add new tasks

• Display a list of tasks with checkboxes to mark as complete

• Include options to edit or delete tasks

• Implement functionality to mark tasks as complete or incomplete

• Add a feature to filter tasks by status (completed/incomplete)
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Q2. Lifecycle methods
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Round duration - 60 minutes
Round difficulty - Medium

Online Coding Test on Calyxpod platform. There were 2 coding questions

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. Brute Force
• For each node in the first list, traverse the entire second list
• Check if any node in the second list coincides with the first list
  • If it does, return that node’s data
  • If it doesn’t, return -1
Space Complexity: O(1)Explanation:
O(1)
 
Since we only use constant space.
Time Complexity: O(m*n) - For 2d arraysExplanation:
O(N * M), where N and M are the lengths of the first and second linked lists respectively.&n...read more
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Q2. 
Most Frequent Non-Banned Word Problem Statement
Given a paragraph consisting of letters in both lowercase and uppercase, spaces, and punctuation, along with a list of banned words, your task is to find th...read more
Ans. Brute Force
1. To find the frequency of each word we need to extract the words from the paragraph.
2. So we will convert all the punctuation to space in the paragraph and lowercase alphabets to uppercase.
3. Now we can use the library function (e.g sstream in C++) to extract words from the paragraph in an array of strings say WORDS.
4. We will iterate over WORDS and do:
   1. Iterate over the banned array and check if the current word is pre...read more
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Round duration - 70 minutes
Round difficulty - Easy

Advance Subjective Round on Calyxpod platform: 5 questions. One question was related to data structures and algorithms. Other 4 were related to Html, CSS and Javascript.

Q1. 
Balanced Parentheses Combinations
Given an integer N representing the number of pairs of parentheses, find all the possible combinations of balanced parentheses using the given number of pairs.
Explanati...read more
Ans. Recursion
The idea is to generate all possible combinations and check whether the combination is the combination of balanced parentheses or not. We have two choices whether to consider ‘(‘ or ‘)’.
When the number of closing brackets is greater than the number of opening brackets we can consider taking ‘)’ in the sequence and in the other case we can consider taking ‘(‘ for all numbers of opening brackets until the number...read more
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Round duration - 90 Minutes
Round difficulty - Easy

You are given three ds coding questions which you have to solve within 90 mins.
The questions are easy to medium level for this round

Q1. 
Non-Decreasing Array Problem Statement
Given an integer array ARR of size N, determine if it can be transformed into a non-decreasing array by modifying at most one element.
An array is defined as non-de...read more
Ans. 
The solution checks if an integer array can become non-decreasing by modifying at most one element.
• Iterate through the array and check if there are more than one decreasing pairs of elements.

• If there are more than one decreasing pairs, return false.

• If there is only one decreasing pair, check if modifying one of the elements can make the array non-decreasing.

• If modifying the element at index i-1 or i can make the array ...read more
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Q2. 
Sort Linked List Based on Actual Values
You are given a Singly Linked List of integers that is initially sorted according to the absolute values of its elements. Your task is to sort this Linked List base...read more
Ans. 
The task is to sort a singly linked list based on actual values instead of absolute values.
• Traverse the linked list and store the values in an array

• Sort the array using any sorting algorithm

• Create a new linked list using the sorted array

• Return the new linked list
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Q3. 
Diameter of a Binary Tree Problem Statement
Given a binary tree, return the length of its diameter. The diameter of a binary tree is defined as the length of the longest path between any two nodes in the ...read more
Ans. 
The diameter of a binary tree is the length of the longest path between any two end nodes in the tree.
• The diameter of a binary tree can be calculated by finding the maximum of the following three values: 1) the diameter of the left subtree, 2) the diameter of the right subtree, and 3) the longest path that passes through the root node.

• To find the diameter of a binary tree, we can use a recursive approach. We calculate ...read more
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Round duration - N/A
Round difficulty - Medium

Round duration - 120 Minutes
Round difficulty - Hard

This round focus on advanced Js concepts and the tech stack I used in my projects.

Q1. 
Find Unique Element in Array
You have been provided an integer array/list ARR of size N. Here, N is equivalent to 2M + 1 where each test case has M numbers appearing twice and one number appearing exactly...read more
Ans. 
The task is to find the unique number in an array where all other numbers occur twice.
• The array size is given by N = 2M + 1, where M is the number of elements occurring twice.

• Loop through the array and use a hashmap to count the occurrences of each number.

• Return the number with a count of 1, as it is the unique number.
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Round duration - 60 Minutes
Round difficulty - Easy

It was a late night round as i have already had the previous 3 rounds at the same day. The HR asked about my experience regarding the previous rounds and also some situation based questions.

Round duration - 60 Minutes
Round difficulty - Medium

This was the DSA questions round. There were 2 questions. and both were basic questions.

Q1. 
Check If Linked List Is Palindrome
Given a singly linked list of integers, determine if the linked list is a palindrome.
Explanation:
A linked list is considered a palindrome if it reads the same forwar...read more
Ans. Using Stack
The idea is to store the list values in a stack and then compare the values in the list with the values in the stack.
 
Algorithm:
1. Traverse the list from head to tail and push every node in the stack.
2. Make a pointer ‘cur’ which initially points to the head node.
3. If value at ‘cur’ is not equal to the top element of the stack, then the given list is not a palindrome
4. Else, move the ‘cur’ pointer to its next node...read more
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Q2. 
Segregate Odd-Even Problem Statement
In a wedding ceremony at NinjaLand, attendees are blindfolded. People from the bride’s side hold odd numbers, while people from the groom’s side hold even numbers. For...read more
Ans. Iterative Approach 1
As we have to arrange the nodes such that all the odd nodes should come before all the even nodes, we can move all the even valued nodes from their current positions to the end of the linked list. 
 
Algorithm:
 
• Initialise a pointer ‘LAST_NODE’ by NULL.
• Traverse the linked list to the end and get the last node of the list which will be pointed by ‘LAST_NODE’.
• Initialize a pointer ‘NEW_END’...read more
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Round duration - 90 Minutes
Round difficulty - Easy

This was a subjective round where we have to code HTML, CSS, and JS. We were not allowed to use any external editor and their editor was just plain notepad so we couldn't even see the output but still, we completed it. Everyone at my college passed this round.

Round duration - 10080 Minutes
Round difficulty - Easy

Round duration - 120 Minutes
Round difficulty - Medium

In this round, the interviewer asked me to turn on screen mirroring. And then he gave me 1 more design which I needed to create in front of him in the next 2 hours. In the previous round, the focus was on HTML and CSS but in this round, the major focus was on JS. You are allowed to use google but not copy-paste the whole code.

Round duration - 90 Minutes
Round difficulty - Hard

This was an online interview with one of their employees. My interview was taken by their front-end lead. She was very helpful during the interview. You are allowed to search for documentation.

Round duration - 90 Minutes
Round difficulty - Easy

This was also a front-end interview round. The interviewer was again very helpful and I was allowed to google.

Round duration - 180 Minutes
Round difficulty - Medium

General Questions Like - Introduction & How all the round have gone so far

Round duration - 90 Minutes
Round difficulty - Medium

One-to-One Interview based on DSA and Front-End Technologies including HTML, CSS & JS.

Q1. 
Remove Duplicates Problem Statement
You are given an array of integers. The task is to remove all duplicate elements and return the array while maintaining the order in which the elements were provided.
...read more
Ans. Brute Force
We will traverse the whole array and check if that element previously occurred or not.
 
The steps are as follows:
• We initialize a vector ‘ans’ to store the final non-duplicate elements.
• We will iterate over all the elements of the array, i.e., i = 0 to i = N - 1:
  • We will iterate over all the elements of the array excluding present element, i.e., j = 0 to j = N - 1:
    • If we get such positions such that arr[i] e...read more
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Round duration - 90 Minutes
Round difficulty - Hard

One-to-One Interview based on Front-End Technologies including HTML, CSS & JS.

In the last 10-20 minutes, some behavioral questions were asked:
1 How would you grade yourself in the interview so far?
2. You are present in a team and you have to convince your team members & client that your approach is better than the other team members.
3. You are the team leader & you have to point out & convey the negative points of a member of your team without getting him/her hurt.
- At last, they asked me if I have questions for them( I asked 2 questions ) & then the interview ended.

Q1. 
Merge K Sorted Arrays Problem Statement
Given 'K' different arrays that are individually sorted in ascending order, merge all these arrays into a single array that is also sorted in ascending order.
Inpu...read more
Ans. Sorting
 
1. Create an output array ‘RESULT’.
2. Traverse all the given arrays from start to end and insert all the elements in the output array ‘RESULT’.
3. Sort the ‘RESULT’ and return it.
Space Complexity: O(2^n)Explanation:
O(N * K), Where ‘K’ is the number of arrays and ‘N’ is the average number of elements in every array.
 
We are using an array/list of size O(N * K) to store all the elements of the ‘K’ arrays/lists. T...read more
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