Blackrock Front end Developer Interview Questions and Answers

Q1. Basic Javascript questions. Object, Arrow function.
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2 DSA questions were asked,one was of binary search and another was of cycle linked list

Q1. Round 1 1.Basic JS question 2.Tricky indepth question who answer you would have to logically conclude/ educative guess Eg: 3. Why class are in React immutable but props mutable What happens to local sess...read more
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1.Complex coding round.
2.Explain any independent project you have done

Round duration - 30 minutes
Round difficulty - Easy

It was in the day time. I was asked the programming language of my choice. It was mostly focused on programming fundamentals. I was asked 2 questions based on Data Structures and Algorithms.

Q1. How can you detect a loop in a linked list?
Ans. 
A loop in a linked list can be detected using Floyd's Cycle Detection Algorithm.
• Use two pointers - slow and fast, where slow moves one step at a time and fast moves two steps at a time.

• If there is a loop, the two pointers will eventually meet at some point within the loop.

• To detect the start of the loop, reset one pointer to the head and move both pointers one step at a time until they meet again.
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Round duration - 30 minutes
Round difficulty - Easy

This round was mostly focused on my resume and projects.

Q1. Tell me about your projects.
Ans. 
I worked on several projects, including a web app for task management and a machine learning model for sentiment analysis.
• Developed a task management web app using React and Node.js, allowing users to create, update, and delete tasks.

• Implemented a machine learning model using Python and scikit-learn to analyze customer reviews and predict sentiment.

• Created a personal portfolio website to showcase my projects and skills...read more
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Round duration - 30 minutes
Round difficulty - Easy

It was in the evening. I went to their office in Gurgaon. It was taken by one of the technology director who had a lot of experience. 
 

Round duration - 90 minutes
Round difficulty - Medium

There were 33 questions in total. The objective questions were simple.

Q1. 
Sort Big List Dates Problem Statement
Mary is an enthusiastic party-goer who struggles with remembering event dates. Help Mary by sorting a given list of event dates in an ascending order.
Example:
Inpu...read more
Ans. 
Sort a list of event dates in ascending order based on year, month, and day.
• Sort the list of dates based on year, then month, and finally day.

• Use a sorting algorithm to rearrange the dates in ascending order.

• Ensure the constraints are met for each date in the list.
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Q2. 
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. 
Given an array and a target sum, find all pairs of elements that add up to the target sum.
• Iterate through the array and for each element, check if the complement (target sum - current element) exists in a hash set.

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

• Sort the pairs based on the first element and then the second element.

• Handle edge cases like duplicate elements and pairs with the same values.

• Example...read more
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Q3. 
Maximum Sum Problem Statement
Given an integer N, your task is to recursively break it into three integer parts: N / 2, N / 3, and N / 4. You need to compute the maximum sum possible by dividing the numbe...read more
Ans. 
Given an integer N, recursively break it into three parts and find the maximum sum possible.
• Recursively divide N into N/2, N/3, and N/4 to find the maximum sum

• Compare the sum obtained by dividing N with the sum of N itself

• Return the maximum sum for each test case
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