Infosys Mern Stack Developer Interview Questions and Answers

Round duration - 90 minutes
Round difficulty - Medium

Timing was around 10am
It was quite a normal online examination kind of environment 
People from the company were there to invigilate 
All were quite nice and helpful in case the exam got stuck

Q1. 
Ninja and Alien Language Order Problem
An alien dropped its dictionary while visiting Earth. The Ninja wants to determine the order of characters used in the alien language, based on the given list of wor...read more
Ans. 
Determine the order of characters in an alien language based on a list of words.
• Create a graph data structure to represent the relationships between characters in the words.

• Perform a topological sort on the graph to find the order of characters.

• Return the smallest lexicographical order of characters as the result.
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Q2. 
Check Duplicate Within K Distance
Given an array of integers arr of size N and an integer K, determine if there are any duplicate elements within a distance of K from each other in the array. Return "true...read more
Ans. 
Check if there are any duplicate elements within a distance of K from each other in the array.
• Iterate through the array and keep track of the indices of elements using a hashmap.

• For each element, check if it already exists in the hashmap within distance K.

• Return true if a duplicate is found within distance K, otherwise return false.
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Round duration - 30 minutes
Round difficulty - Medium

Timing was 2pm when it started
Interviewer was polite

Q1. 
Kth Largest Element Problem Statement
Ninja enjoys working with numbers, and Alice challenges him to find the Kth largest value from a given list of numbers.
Input:
The first line contains an integer 'T...read more
Ans. 
The task is to find the Kth largest element in a given list of numbers for each test case.
• Read the number of test cases 'T'

• For each test case, read the number of elements 'N' and the Kth largest number to find 'K'

• Sort the array in descending order and output the Kth element
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Round duration - 20 minutes
Round difficulty - Easy

Timing was 9 am onwards 
Interviewer was good enough

Round duration - 90 minutes
Round difficulty - Hard

Exam was in the morning in 2nd shift. It was a difficult .

Q1. 
Sum of Even & Odd Digits
You need to determine the sum of even digits and odd digits separately from a given integer.
Input:
The first line of input is an integer T representing the number of test c...read more
Ans. 
Implement a function to find the sum of even and odd digits separately in a given integer.
• Iterate through each digit of the integer and check if it is even or odd.

• Keep track of the sum of even and odd digits separately.

• Return the sums of even and odd digits for each test case.
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Round duration - 30 minutes
Round difficulty - Hard

It was in the morning and there were approx 500 candidates for interview. Interviewers were very nice and cooperative.

Q1. What SQL questions do you have related to joins?
Ans. 
SQL questions related to joins
• Types of joins in SQL (inner join, left join, right join, full outer join)

• Difference between inner join and outer join

• Common join conditions (using ON vs WHERE)

• Handling NULL values in joins

• Performance considerations when using joins
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Round duration - 10 minutes
Round difficulty - Medium

It was in the morning and interviewer was very nice and polite.