Redback IT Solutions Software Developer Intern Interview Questions and Answers

Round duration - 90 Minutes
Round difficulty - Medium

This was an online coding round where we had 2 questions of Medium to Hard level of difficulty to solve under 90 minutes. I was able to solve the 2nd question fully and the 1st one partially. 10 students were shortlisted for further rounds and I was one of them.

Q1. 
Longest Palindromic Substring Problem Statement
You are provided with a string STR of length N. The goal is to identify the longest palindromic substring within this string. In cases where multiple palind...read more
Ans. 
Given a string, find the longest palindromic substring, choosing the one with the smallest start index if multiple exist.
• Iterate through the string and expand around each character to find palindromes

• Keep track of the longest palindrome found and its starting index

• Return the longest palindromic substring with the smallest start index
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Q2. 
Count Subarrays with Given XOR Problem Statement
You are given an array of integers ARR and an integer X. Your task is to determine the number of subarrays of ARR whose bitwise XOR is equal to X.
Example...read more
Ans. 
Count the number of subarrays in an array whose XOR is equal to a given value.
• Iterate through the array and keep track of XOR values and their frequencies using a hashmap.

• For each element, calculate the XOR with the previous elements to find subarrays with XOR equal to the given value.

• Use the hashmap to efficiently count the number of subarrays with the desired XOR value.

• Handle edge cases like XOR value being 0 separat...read more
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Round duration - 70 Minutes
Round difficulty - Medium

This was a preety intense round where I had to solve 3 algorithmic questions under 70 minutes. I first explained my approach for each of these questions and also discussed why they were optimal in the first place with their respective time and space compleixities. The interviewer was quite impressed at the end of the round.

Q1. 
Kth Largest Number Problem Statement
You are given a continuous stream of numbers, and the task is to determine the kth largest number at any moment during the stream.
Explanation:
A specialized data st...read more
Ans. 
Design a data structure to find the kth largest number in a continuous stream of integers.
• Design a specialized data structure to handle continuous stream of numbers

• Implement add(DATA) function to add integers to the pool

• Implement getKthLargest() function to retrieve the kth largest number

• Maintain the pool of numbers and update it based on queries

• Output the kth largest number for each Type 2 query
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Q2. 
Merge Two Sorted Linked Lists Problem Statement
You are provided with two sorted linked lists. Your task is to merge them into a single sorted linked list and return the head of the combined linked list.
...read more
Ans. 
Merge two sorted linked lists into a single sorted linked list without using additional space.
• Create a dummy node to start the merged list

• Compare the values of the two linked lists and append the smaller value to the merged list

• Move the pointer of the merged list and the pointer of the smaller value's linked list

• Continue this process until one of the linked lists is fully traversed

• Append the remaining elements of the o...read more
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Q3. 
Stack using Two Queues Problem Statement
Develop a Stack Data Structure to store integer values using two Queues internally.
Your stack implementation should provide these public functions:
Explanation:
...read more
Ans. 
Implement a stack using two queues to store integer values with specified functions.
• Use two queues to simulate stack operations efficiently.

• Maintain the top element in one of the queues for easy access.

• Ensure proper handling of edge cases like empty stack or invalid operations.

• Example: Push elements 5, 10, 15; Pop element 15; Check top element 10; Check size of stack; Check if stack is empty.
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Round duration - 30 Minutes
Round difficulty - Easy

This was a typical HR round with some standard Behavioral questions.

Q1. Can you tell me something about yourself?
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Q2. What do you know about the company?
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