Ajayvision Education Senior Android Developer 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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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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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 - 120 minutes
Round difficulty - Easy

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 store the non-alphabet characters in their original positions

• Reverse the letters using two pointers technique

• Combine the reversed letters with the non-alphabet characters to get the final reversed string
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Q2. 
Find the Duplicate Number Problem Statement
Given an integer array 'ARR' of size 'N' containing numbers from 0 to (N - 2). Each number appears at least once, and there is one number that appears twice. Yo...read more
Ans. 
Find the duplicate number in an array of integers from 0 to N-2.
• Iterate through the array and keep track of the frequency of each number using a hashmap.

• Return the number with a frequency greater than 1 as the duplicate number.
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Q3. 
Reverse Array Elements
Given an array containing 'N' elements, the task is to reverse the order of all array elements and display the reversed array.
Explanation:
The elements of the given array need to...read more
Ans. 
Reverse the order of elements in an array and display the reversed array.
• Iterate through the array from both ends and swap the elements until the middle is reached.

• Use a temporary variable to store the element being swapped.

• Print the reversed array after all elements have been swapped.
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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 - Easy

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

Q1. 
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 and reuse previously calculated Fibonacci numbers.

• Start with base cases F(1) and F(2) as 1, then calculate subsequent Fibonacci numbers.

• Optimize the solution to avoid redundant calculations by storing intermediate results.

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

• Example: For N = 5, the 5th F...read more
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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 NOT IN operator to exclude the highest salary from the results

• Order the results in descending order and limit the query to return only the second row
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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 corresponding index in the array for each character encountered.

• 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 database design technique used to structure a relational database in a way that reduces data redundancy and improves data integrity.

• Third Normal Form (3NF) is a level of database normalization where every non-prime attribute of a table is dependent on the primary key.

• To achieve 3NF, a table m...read more
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Round duration - 90 minutes
Round difficulty - Easy

There were two section Aptitude and Coding.

Q1. 
Buy and Sell Stock Problem Statement
Imagine you are Harshad Mehta's friend, and you have been given the stock prices of a particular company for the next 'N' days. You can perform up to two buy-and-sell ...read more
Ans. 
The task is to determine the maximum profit that can be achieved by performing up to two buy-and-sell transactions on a given set of stock prices.
• Iterate through the array of stock prices and calculate the maximum profit that can be achieved by buying and selling at different points.

• Keep track of the maximum profit after the first transaction and the maximum profit overall by considering different combinations of buy a...read more
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Round duration - 60 minutes
Round difficulty - Easy

This was the first technical interview.

Q1. 
Pair Sum Problem Statement
You are given an integer array 'ARR' of size 'N' and an integer 'S'. Your task is to find and return a list of all pairs of elements where each sum of a pair equals 'S'.
Note:
...read more
Ans. 
Find pairs of elements in an array that sum up to a given value, sorted in a specific order.
• Iterate through the array and for each element, check if the complement (S - current element) exists in a hash set.

• Keep track of pairs in a hash set to avoid duplicates.

• Sort the pairs based on the criteria mentioned in the question.

• Return the sorted list of pairs.
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Aptitude and coding of 2 hours

Q1. Questions based on sql and dsa
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Basic aptitude questions

3 basic questions they asked

Pointer and SQL related questions

Easy 1 hr test and can be completed easily

Q1. SQL queries more focus on analytic side
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Q2. DSA + OOPS
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