Infosys Mern Stack Developer Interview Questions and Answers

Round duration - 100 Minutes
Round difficulty - Medium

Q1. 
Change Start Node Problem Statement
You are provided with a singly linked list and an integer K. The objective is to make the Kth node from the end of the linked list the starting node of the linked list.
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Ans. 
Given a singly linked list and an integer K, rearrange the list such that the Kth node from the end becomes the starting node.
• Traverse the linked list to find the length and the Kth node from the end.

• Update the pointers to rearrange the list accordingly.

• Handle edge cases like K being equal to 1 or the length of the list.
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Q2. 
Valid Parentheses Problem Statement
Given a string 'STR' consisting solely of the characters “{”, “}”, “(”, “)”, “[” and “]”, determine if the parentheses are balanced.
Input:
The first line contains an...read more
Ans. 
Check if given strings containing parentheses are balanced or not.
• Use a stack to keep track of opening parentheses

• Iterate through the string and push opening parentheses onto the stack

• When a closing parentheses is encountered, pop from the stack and check if it matches the corresponding opening parentheses

• If stack is empty at the end and all parentheses are matched, the string is balanced
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Round duration - 120 Minutes
Round difficulty - Medium

Q1. 
Alien Dictionary Problem Statement
You are provided with a sorted dictionary (by lexical order) in an alien language. Your task is to determine the character order of the alien language from this dictiona...read more
Ans. 
Given a sorted alien dictionary in an array of strings, determine the character order of the alien language.
• Iterate through the dictionary to build a graph of character dependencies based on adjacent words.

• Perform a topological sort on the graph to determine the character order.

• Return the character array representing the order of characters in the alien language.
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Q2. 
Chocolate Distribution Problem
You are given an array/list CHOCOLATES of size 'N', where each element represents the number of chocolates in a packet. Your task is to distribute these chocolates among 'M'...read more
Ans. 
Distribute chocolates among students to minimize the difference between the largest and smallest number of chocolates.
• Sort the array of chocolates in ascending order.

• Iterate through the array and find the minimum difference between the elements by considering 'M' elements at a time.

• Return the minimum difference found as the result.
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Round duration - 120 Minutes
Round difficulty - Medium

Q1. 
Inplace Rotate Matrix 90 Degrees Anti-Clockwise
You are provided with a square matrix of non-negative integers of size 'N x N'. The task is to rotate this matrix by 90 degrees in an anti-clockwise directi...read more
Ans. 
Rotate a square matrix by 90 degrees anti-clockwise without using extra space.
• Iterate through each layer of the matrix from outer to inner layers

• Swap elements in groups of 4 to rotate them in place

• Handle odd-sized matrices separately by adjusting the loop boundaries
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Q2. 
Flip The Bits Problem Statement
Given a binary string S of length N where initially all characters are '1', perform exactly M operations, choosing from four specific operations, and determine how many dis...read more
Ans. 
Count the number of distinct final strings possible after performing a given number of operations on a binary string.
• Iterate through all possible combinations of operations to determine the final string after each operation.

• Use bitwise operations to efficiently flip the bits based on the chosen operation.

• Keep track of distinct final strings using a set data structure.

• Return the size of the set as the number of distinct...read more
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Round duration - 120 Minutes
Round difficulty - Medium

Q1. 
Next Greater Element Problem Statement
Given a list of integers of size N, your task is to determine the Next Greater Element (NGE) for every element. The Next Greater Element for an element X is the firs...read more
Ans. 
Find the Next Greater Element for each element in a list of integers.
• Iterate through the list of integers from right to left.

• Use a stack to keep track of elements for which the Next Greater Element is not yet found.

• Pop elements from the stack until a greater element is found or the stack is empty.

• Assign the Next Greater Element as the top element of the stack or -1 if the stack is empty.
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