Epsilon Software Developer Interview Questions and Answers

Held on interview bit. 3 ques were asked. Questions were from range query and DP.

Q1. 1 Hard DSA question. Given a sequence of positive numbers, make it a non-decreasing sequence. Operation allowed: adjacent elements can be added to form a single element. What is the minimum no of operatio...read more
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Q1. Asked two array and string dsa questions of medium-hard level
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Q1. What is Indexing in Mysql
Ans. 
Indexing in MySQL is a technique to improve the performance of database queries by creating a data structure that allows for faster data retrieval.
• Indexes are created on one or more columns of a table.

• They help in speeding up the search, sorting, and joining of data.

• Indexes can be created using different algorithms like B-tree, hash, or bitmap.

• Using indexes appropriately can significantly enhance query performance.

• Exam...read more
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Q2. Opps concepts in php
Ans. 
Object-oriented programming concepts in PHP
• Encapsulation: bundling data and methods together in a class

• Inheritance: creating new classes based on existing ones

• Polymorphism: using a single interface to represent different types

• Abstraction: hiding unnecessary details and exposing only essential features

• Class: blueprint for creating objects

• Object: instance of a class

• Method: function defined inside a class

• Property: variabl
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Q1. Basic JavaScript and React.js questions
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Q2. Questions on functions, hooks and DOM
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Q3. Questions on SSR
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Q4. Questions on strings and arrays
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Api related questions

It will be around 3 hours and 2 questions of leetcode hard difficulty will be asked in the interview and 1 question is of codeforces 2400+ difficulty question.

Q1. 1-2 DSA medium-hard difficulty question will be asked.
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Q2. CS fundamentals in depth had been asked in the ending of the interview.
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Q1. System Design problem was asked.
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Q1. This is a cultural fit round. Common HR question was asked.
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Round duration - 75 minutes
Round difficulty - Easy

This round was conducted in Hackerrank portal for a total duration of 75 minutes and was divided into 4 sections.

1st Section : Aptitude Section : 14 questions , 28 minutes
2nd Section : Technical Section : 12 questions , 17 minutes
3rd Section :1 coding Questions : 20 minutes+30 minutes

This Round was Conducted on Hackerrank (Webcam Enabled).

Q1. Given a problem statement and a piece of code, how would you find and correct the bug in the code?
Ans. 
To find and correct a bug in code, analyze problem statement, review code, use debugging tools, and test different scenarios.
• Understand the problem statement and expected output

• Review the code for syntax errors, logical errors, and potential bugs

• Use debugging tools like breakpoints, print statements, and IDE debuggers

• Test the code with different inputs and edge cases to identify the bug

• Make necessary corrections and re
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Q2. 
Nodes at Distance K from Target Node in Binary Tree
Given a Binary Tree of distinct integers and two integers, target and K, return a list of values of all nodes located at a distance K from the target no...read more
Ans. 
Find nodes at distance K from target node in a Binary Tree.
• Use BFS to traverse the tree and keep track of the distance of each node from the target node.

• Maintain a set to keep track of visited nodes to avoid revisiting them.

• Return the values of nodes at distance K from the target node.
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Round duration - 90 minutes
Round difficulty - Medium

I was shared a link of Google Meet and the Google Docs was shared where there was 1 coding problem to be coded there and then the code was run on an IDE to check the sample tests.
Then the interview was followed by a lot of Operating System and Computer System Architecture Questions.
There were 2 Interviewers and both were helpful.
The timing was from 2:30 PM to 4:00 PM

Q1. 
Subarray Challenge: Largest Equal 0s and 1s
Determine the length of the largest subarray within a given array of 0s and 1s, such that the subarray contains an equal number of 0s and 1s.
Input:
Input beg...read more
Ans. 
Find the length of the largest subarray with equal number of 0s and 1s in a given array.
• Iterate through the array and maintain a count of 0s and 1s encountered so far.

• Store the count difference in a hashmap with the index as key.

• If the same count difference is encountered again, the subarray between the two indices has equal 0s and 1s.

• Return the length of the longest subarray found.
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Round duration - 45 minutes
Round difficulty - Easy

The round was held on Google Meet with HR from 2:30 PM to 3:15 PM.
The HR was friendly and asked the basic questions.