HackerRank Front end Engineer Interview Questions and Answers

Round duration - 120 minutes
Round difficulty - Hard

This round was very difficult. I never do these much difficulty level of coding questions. But i give my best, and just do every questions by using step by step process.

Q1. 
Hourglass Pattern Problem Statement
Given an integer 'N', print an hourglass pattern based on the value of 'N'.
Input:
The first and only line of input contains an integer, denoting the value of N.
Out...read more
Ans. 
Print an hourglass pattern based on the given integer 'N'.
• Read the integer 'N' as input

• Print the top half of the hourglass pattern with decreasing numbers

• Print the bottom half of the hourglass pattern with increasing numbers

• Handle the constraints for 'N' values between 1 and 50
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Q2. 
BFS Traversal in a Graph
Given an undirected and disconnected graph G(V, E) where V vertices are numbered from 0 to V-1, and E represents edges, your task is to output the BFS traversal starting from the ...read more
Ans. 
BFS traversal in a disconnected graph starting from vertex 0.
• Use BFS algorithm to traverse the graph starting from vertex 0.

• Explore neighbor nodes first before moving to the next level neighbors.

• Consider bidirectional edges in an undirected graph.

• Output the BFS traversal sequence for each test case in a separate line.

• Ensure the BFS path starts from vertex 0 and print connected nodes in numerical sort order.
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Q3. 
Sort a Stack Problem Statement
You are given a stack. Your task is to sort the elements within the stack in ascending order using only push and pop operations. You are allowed to use one additional stack ...read more
Ans. 
Sort a given stack in ascending order using only push and pop operations with the help of an additional stack.
• Use one additional stack to assist in sorting the elements.

• Pop elements from the input stack and push them onto the auxiliary stack in sorted order.

• Keep track of the current minimum element to maintain ascending order.

• Pop elements from the auxiliary stack back to the input stack to get the sorted order.
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Round duration - 90 minutes
Round difficulty - Easy

This round is also coding round in this round we have a small video call interaction too, in which hr ask few questions to only those whose coding question is correct.

Q1. 
Next Smaller Palindrome Problem Statement
You are given a palindrome number represented as a string S. Your task is to find the largest palindrome number that is strictly less than S.
Example:
Input:
T...read more
Ans. 
Find the largest palindrome number strictly less than a given palindrome number.
• Iterate from the middle towards the start of the number and decrement the digits to create the largest palindrome less than the given number.

• Handle cases where the number is all '9's by changing the middle digit to '9' and decrementing the rest of the digits.

• If the number has an odd length, simply mirror the first half to create the largest
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Q2. 
Rotting Oranges Problem Statement
You are given a grid containing oranges where each cell of the grid can contain one of the three integer values:
• 0 - representing an empty cell
• 1 - representing a fre...read more
Ans. 
Find minimum time to rot all fresh oranges adjacent to rotten oranges in a grid.
• Use Breadth First Search (BFS) to simulate the rotting process.

• Track the time taken to rot all fresh oranges.

• Return -1 if all fresh oranges cannot be rotten.

• Handle edge cases like empty grid or no fresh oranges.
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