Gainup Industries Junior Software Engineer Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Easy

It comprised of general aptitude questions and two coding questions. It was an offline test.

Q1. 
N Queens Problem
Given an integer N, find all possible placements of N queens on an N x N chessboard such that no two queens threaten each other.
Explanation:
A queen can attack another queen if they ar...read more
Ans. 
The N Queens Problem involves finding all possible placements of N queens on an N x N chessboard where no two queens threaten each other.
• Use backtracking algorithm to explore all possible configurations.

• Keep track of rows, columns, and diagonals to ensure queens do not attack each other.

• Generate and print valid configurations where queens are placed safely.

• Consider constraints and time limit for efficient solution.

• Exam...read more
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Q2. 
Sort 0 1 2 Problem Statement
Given an integer array arr of size 'N' containing only 0s, 1s, and 2s, write an algorithm to sort the array.
Input:
The first line contains an integer 'T' representing the n...read more
Ans. 
Sort an integer array containing only 0s, 1s, and 2s in linear time complexity.
• Use three pointers to keep track of the positions of 0s, 1s, and 2s in the array.

• Iterate through the array and swap elements based on the values encountered.

• Achieve sorting in a single scan over the array without using any extra space.
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Round duration - 60 minutes
Round difficulty - Easy

After having a technical discussion about my CV. He gave me two questions to code.

Q1. 
Ninja and Substrings Problem Statement
Ninja has to determine all the distinct substrings of size two that can be formed from a given string 'STR' comprising only lowercase alphabetic characters. These su...read more
Ans. 
Find all unique contiguous substrings of size two from a given string.
• Iterate through the string and extract substrings of size two

• Use a set to store unique substrings

• Return the set as an array of strings
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Q2. 
Cycle Detection in a Singly Linked List
Determine if a given singly linked list of integers forms a cycle or not.
A cycle in a linked list occurs when a node's next points back to a previous node in the ...read more
Ans. 
Detect if a singly linked list forms a cycle by checking if a node's next points back to a previous node.
• Traverse the linked list using two pointers, one moving one step at a time and the other moving two steps at a time.

• If the two pointers meet at any point, there is a cycle in the linked list.

• If one of the pointers reaches the end of the list (null), there is no cycle.
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Round duration - 30 minutes
Round difficulty - Easy

This was supposed to be the HR round but out of surprise the interviewer started by giving me a question to code. 
After I approached this question with the right solution he just asked about my family. After that he said to wait. After half an hour the results were announced. A total of three students were hired and I was amongst one of them.

Q1. 
Balanced Parentheses Combinations
Given an integer N representing the number of pairs of parentheses, find all the possible combinations of balanced parentheses using the given number of pairs.
Explanati...read more
Ans. 
Generate all possible combinations of balanced parentheses for a given number of pairs.
• Use recursion to generate all possible combinations of balanced parentheses.

• Keep track of the number of open and close parentheses used in each combination.

• Return the valid combinations as an array of strings.
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Round duration - 40 minutes
Round difficulty - Medium

Asked about time complexity of algorithm, puzzles, DBMS, cutting edge technologies etc. What are indexes?

Q1. 
Flip Bits Problem Explanation
Given an array of integers ARR of size N, consisting of 0s and 1s, you need to select a sub-array and flip its bits. Your task is to return the maximum count of 1s that can b...read more
Ans. 
Given an array of 0s and 1s, find the maximum count of 1s by flipping a sub-array at most once.
• Iterate through the array and keep track of the maximum count of 1s obtained by flipping a sub-array.

• Consider flipping a sub-array from index i to j and calculate the count of 1s in the resulting array.

• Return the maximum count of 1s obtained by flipping a sub-array at most once.
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Round duration - 20 minutes
Round difficulty - Medium

Asked 1 standard algorithm

Q1. 
Number of Islands Problem Statement
You are provided with a 2-dimensional matrix having N rows and M columns, containing only 1s (land) and 0s (water). Your goal is to determine the number of islands in t...read more
Ans. 
Count the number of islands in a 2D matrix of 1s and 0s.
• Iterate through the matrix and perform depth-first search (DFS) to find connected 1s.

• Mark visited cells to avoid redundant traversal.

• Increment island count whenever a new island is encountered.
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It was an 1hr interview session

Q1. Find the occurrence of each element in an array
Ans. 
Count the occurrence of each element in an array of strings
• Iterate through the array and use a hashmap to store the count of each element

• If element already exists in the hashmap, increment its count by 1

• Return the hashmap with element counts
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Q1. Tell me about yourself
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All three questions are leetcode medium level.

10th level aptitude problem.

Q1. Discuss about my current project and DBMS and mysql
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Round duration - 120 minutes
Round difficulty - Medium

Timing was 9: 30 AM. Platform was quite good and easy to understand.

Q1. 
Reverse Only Letters Problem Statement
You are given a string S. The task is to reverse the letters of the string while keeping non-alphabet characters in their original position.
Example:
Input:
S = "...read more
Ans. 
Reverse the letters of a string while keeping non-alphabet characters in their original position.
• Iterate through the string and maintain two pointers, one at the start and one at the end, to reverse only the letters

• Use isalpha() function to check if a character is an alphabet or not

• Swap the letters at the two pointers until they meet in the middle
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Q2. 
Find Duplicates in an Array
Given an array ARR of size 'N', where each integer is in the range from 0 to N - 1, identify all elements that appear more than once.
Return the duplicate elements in any orde...read more
Ans. 
Find duplicates in an array of integers within a specified range.
• Iterate through the array and keep track of the count of each element using a hashmap.

• Return elements with count greater than 1 as duplicates.

• Time complexity can be optimized to O(N) using a set to store duplicates.

• Example: For input [0, 3, 1, 2, 3], output should be [3].
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Q3. 
Pancake Sorting Problem Statement
You are given an array of integers 'ARR'. Sort this array using a series of pancake flips. In each pancake flip, you need to:
Choose an integer 'K' where 1 <= 'K' <...read more
Ans. 
Sort an array using pancake flips and return the sequence of flips made.
• Iterate through the array and find the position of the maximum element in each iteration.

• Perform pancake flips to move the maximum element to the correct position.

• Continue this process until the array is sorted.

• Return the sequence of positions from where flips were made.
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Q4. 
Sum of Digits Problem Statement
Given an integer 'N', continue summing its digits until the result is a single-digit number. Your task is to determine the final value of 'N' after applying this operation ...read more
Ans. 
Given an integer, find the final single-digit value after summing its digits iteratively.
• Iteratively sum the digits of the given integer until the result is a single-digit number

• Output the final single-digit integer for each test case

• Handle multiple test cases efficiently
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Round duration - 30 minutes
Round difficulty - Medium

Timing was 9:30 AM. The interviewer was very nice.

Q1. 
Fibonacci Number Verification
Identify if the provided integer 'N' is a Fibonacci number.
A number is termed as a Fibonacci number if it appears in the Fibonacci sequence, where each number is the sum of...read more
Ans. 
Check if a given number is a Fibonacci number or not.
• Iterate through the Fibonacci sequence until you find a number greater than or equal to the given number.

• Check if the given number matches the Fibonacci number found in the sequence.

• If the number matches, output 'YES'; otherwise, output 'NO'.
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Q2. Write an SQL query to find the second highest salary from a table.
Ans. 
SQL query to find the second highest salary from a table
• Use the MAX() function to find the highest salary

• Use the WHERE clause to exclude the highest salary

• Order the salaries in descending order and limit the result to 1
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Round duration - 30 Minutes
Round difficulty - Medium

Timing was 12 PM. Interviewer was not good.

Q1. 
Character Frequency Problem Statement
You are given a string 'S' of length 'N'. Your task is to find the frequency of each character from 'a' to 'z' in the string.
Example:
Input:
S : abcdg
Output:
1...read more
Ans. 
The task is to find the frequency of each character from 'a' to 'z' in a given string.
• Create an array of size 26 to store the frequency of each character from 'a' to 'z'.

• Iterate through the string and increment the count of the corresponding character in the array.

• Print the array of frequencies as the output for each test case.
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Q2. What is normalization and can you explain the concept of Third Normal Form (3NF)?
Ans. 
Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity.
• Normalization is a technique used to organize data in a database efficiently.

• Third Normal Form (3NF) is a level of normalization that ensures that data is stored in a way that prevents certain types of data anomalies.

• In 3NF, every non-prime attribute is fully functionally dependent on the primary key.

• For exampl...read more
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Round duration - 90 minutes
Round difficulty - Medium

A time range is given you can attempt with in that time and once started you cant resume .

Q1. 
Sort String with Alternate Lower and Upper Case
Given a string STR containing both lowercase and uppercase letters, the task is to sort the string so that the resulting string contains uppercase and lower...read more
Ans. 
Sort a string with alternate lowercase and uppercase letters in sorted order.
• Create two separate arrays for lowercase and uppercase letters.

• Sort both arrays individually.

• Merge the two arrays alternately to form the final sorted string.
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Q2. 
Remove Invalid Parentheses
Given a string containing only parentheses and letters, your goal is to remove the minimum number of invalid parentheses to make the input string valid and return all possible v...read more
Ans. 
Given a string with parentheses and letters, remove minimum invalid parentheses to make it valid and return all possible valid strings.
• Use BFS to explore all possible valid strings by removing parentheses one by one

• Keep track of visited strings to avoid duplicates

• Return all unique valid strings obtained after removing minimum number of parentheses
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Q3. 
Nth Fibonacci Number Problem Statement
Calculate the Nth term in the Fibonacci sequence, where the sequence is defined as follows: F(n) = F(n-1) + F(n-2), with initial conditions F(1) = F(2) = 1.
Input:
...read more
Ans. 
Calculate the Nth Fibonacci number efficiently using dynamic programming.
• Use dynamic programming to store previously calculated Fibonacci numbers to avoid redundant calculations.

• Start with base cases F(1) and F(2) as 1, then iterate to calculate F(N) efficiently.

• Time complexity can be optimized to O(N) using dynamic programming.

• Example: For N = 5, the 5th Fibonacci number is 5.
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Q4. 
Find the Kth Row of Pascal's Triangle Problem Statement
Given a non-negative integer 'K', determine the Kth row of Pascal’s Triangle.
Example:
Input:
K = 2
Output:
1 1
Input:
K = 4
Output:
1 4 6 ...read more
Ans. 
To find the Kth row of Pascal's Triangle given a non-negative integer K.
• Create an array to store the values of the Kth row of Pascal's Triangle

• Use the formula C(n, k) = C(n-1, k-1) + C(n-1, k) to calculate the values

• Return the array as the output
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