JOBWORLD India Interview Questions and Answers

Round duration - 90 minutes
Round difficulty - Medium

This round had 3 coding questions of Medium to Hard level of difficulty.

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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Q2. 
Trapping Rain Water Problem Statement
You are given a long type array/list ARR of size N, representing an elevation map. The value ARR[i] denotes the elevation of the ith bar. Your task is to determine th...read more
Ans. 
Calculate the total amount of rainwater that can be trapped between given elevations in an array.
• Iterate through the array and calculate the maximum height on the left and right of each bar.

• Calculate the amount of water that can be trapped at each bar by taking the minimum of the maximum heights on the left and right.

• Sum up the trapped water at each bar to get the total trapped water for the entire array.
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Q3. 
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 the minimum time required to rot all fresh oranges adjacent to rotten oranges.
• Create a queue to store the coordinates of rotten oranges and perform BFS to rot adjacent fresh oranges.

• Track the time taken to rot all fresh oranges and return -1 if not all fresh oranges can be rotten.

• Update the grid with the new state of oranges after each second.

• Handle edge cases such as empty grid or no fresh oranges present.

• Example...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This was a standard DS/Algo round where I was given 2 questions to solve under 60 minutes. I was able to come up with the optimal approach for both the questions and then at the end of the interview I was also asked the famous Die Hard Water Puzzle.

Q1. 
Queue Using Stacks Implementation
Design a queue data structure following the FIFO (First In First Out) principle using only stack instances.
Explanation:
Your task is to complete predefined functions t...read more
Ans. 
Implement a queue using stacks following FIFO principle.
• Use two stacks to simulate a queue.

• For enQueue operation, push elements onto stack1.

• For deQueue operation, if stack2 is empty, pop all elements from stack1 and push onto stack2, then pop from stack2.

• For peek operation, if stack2 is empty, pop all elements from stack1 and push onto stack2, then return top of stack2.

• For isEmpty operation, check if both stack1 and st...read more
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Q2. 
Merge Intervals Problem Statement
You are provided with 'N' intervals, each containing two integers denoting the start time and end time of the interval.
Your task is to merge all overlapping intervals a...read more
Ans. 
Merge overlapping intervals and return sorted list of merged intervals by start time.
• Sort the intervals based on start time.

• Iterate through intervals and merge overlapping ones.

• Return the merged intervals in sorted order.
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Q3. You have a 3-liter jar and a 5-liter jar. How can you measure exactly 4 liters using these two jars?
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Round duration - 60 Minutes
Round difficulty - Medium

This round had 2 coding questions - first one related to Binary Tree and the second one was a simple question from Bit Manipulation. This was followed by some questions from OOPS.

Q1. 
Binary Tree Diameter Problem Statement
You are given a Binary Tree, and you need to determine the length of the diameter of the tree.
The diameter of a binary tree is the length of the longest path betwe...read more
Ans. 
The task is to find the diameter of a binary tree, which is the length of the longest path between any two end nodes in the tree.
• Traverse the tree to find the longest path between two nodes.

• Keep track of the maximum diameter found during traversal.

• The diameter may not necessarily pass through the root node.

• Consider both left and right subtrees while calculating the diameter.

• Example: For input 1 2 3 4 -1 5 6 -1 7 -1 -1
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Q2. 
Power of 2 Problem Statement
Determine if it is possible to reorder the digits of a given integer 'N' such that the resulting number is a power of two. The leading digit must not be zero.
Input:
The fir...read more
Ans. 
The problem involves determining if it is possible to reorder the digits of a given integer to form a power of 2.
• Iterate through all possible permutations of the digits of the given integer.

• Check if any of the permutations form a power of 2.

• Return 1 if a valid permutation is found, else return 0.
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Q3. What are some advantages of using Object-Oriented Programming (OOP)?
Ans. 
Advantages of OOP include code reusability, modularity, and easier maintenance.
• Code reusability: Objects can be reused in different parts of the program, reducing redundancy.

• Modularity: OOP allows for breaking down complex problems into smaller, more manageable parts.

• Easier maintenance: Changes to one part of the codebase do not necessarily affect other parts, making maintenance easier.

• Encapsulation: Data hiding and ab...read more
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Q4. What are access specifiers and what is their significance in Object-Oriented Programming?
Ans. 
Access specifiers define the level of access to class members in Object-Oriented Programming.
• Access specifiers include public, private, protected, and default

• Public members are accessible from outside the class

• Private members are only accessible within the class

• Protected members are accessible within the class and its subclasses

• Default access is when no access specifier is specified
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Round duration - 30 Minutes
Round difficulty - Easy

This was my last round and I hoped it to go good just like the other rounds. The interviewer was very straight to point
and professional. The interview lasted for 30 minutes.

Q1. Why should we hire you?
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Round duration - 60 minutes
Round difficulty - Easy

This was a written coding test with 2 coding questions to be solved in 60 minutes.

Q1. 
Find Missing Number In String Problem Statement
You have a sequence of consecutive nonnegative integers. By appending all integers end-to-end, you formed a string S without any separators. During this pro...read more
Ans. 
Given a string of consecutive nonnegative integers with one missing number, find the missing integer.
• Iterate through the string to find the missing number by checking the consecutive integers.

• If there is more than one missing number, all integers are present, or the string is invalid, return -1.

• Handle cases where the missing number is at the beginning or end of the sequence.

• Consider edge cases such as single-digit numb
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Q2. 
First Non-Repeating Character Problem Statement
You are given a string consisting of English alphabet characters. Your task is to identify and return the first character in the string that does not repeat...read more
Ans. 
The task is to find the first non-repeating character in a string, or return the first character if all characters repeat.
• Iterate through the string to count the frequency of each character

• Find the first character with a frequency of 1, or return the first character if no such character exists

• Handle both uppercase and lowercase characters separately

• Use a hashmap to store character frequencies efficiently
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Round duration - 60 minutes
Round difficulty - Medium

Technical interview round with questions around PHP and DBMS.

Q1. What is connection pooling?
Ans. 
Connection pooling is a technique used to manage a pool of database connections to improve performance and efficiency.
• Connection pooling reduces the overhead of opening and closing database connections for each request.

• It allows multiple clients to reuse a pre-established set of connections to the database.

• Connection pooling helps in improving the scalability and performance of applications by efficiently managing data...read more
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Q2. How would you create a singleton design pattern in PHP 5?
Ans. 
To create a singleton design pattern in PHP 5, use a private static variable to store the instance and a static method to retrieve it.
• Create a private static variable to store the instance of the class.

• Create a private constructor to prevent outside instantiation of the class.

• Create a static method to check if an instance already exists and return it, or create a new instance if it doesn't.
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Q3. Can you write code to connect PHP to MySQL?
Ans. 
Yes, PHP can be used to connect to MySQL by using MySQLi or PDO extensions.
• Use MySQLi extension to connect PHP to MySQL

• Use PDO extension to connect PHP to MySQL

• Example using MySQLi: $conn = new mysqli($servername, $username, $password, $dbname);

• Example using PDO: $conn = new PDO('mysql:host=$servername;dbname=$dbname', $username, $password);
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Q4. What are the different types of errors in PHP?
Ans. 
Different types of errors in PHP include syntax errors, runtime errors, and logical errors.
• Syntax errors: Occur when there is a mistake in the code syntax, preventing the script from running.

• Runtime errors: Happen during script execution, such as division by zero or calling a function that does not exist.

• Logical errors: Difficult to detect as the code runs without errors, but produces incorrect results.

• Fatal errors: St...read more
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Q5. How does session management work in PHP?
Ans. 
Session management in PHP involves storing user data on the server to maintain state between multiple requests.
• Sessions are started using session_start() function in PHP.

• Session data is stored on the server and a unique session ID is sent to the client's browser.

• Session variables can be set, accessed, and unset using $_SESSION superglobal array.

• Sessions can be destroyed using session_destroy() function.
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Round duration - 60 minutes
Round difficulty - Easy

This was a coding test where we had to solve 2 coding questions in 60 minutes.

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 to find the maximum profit that can be achieved by buying and selling stocks.

• Keep track of the maximum profit that can be obtained by performing up to two transactions.

• Consider all possible combinations of buying and selling stocks to...read more
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Q2. 
Subsequences of String Problem Statement
You are provided with a string 'STR' that consists of lowercase English letters ranging from 'a' to 'z'. Your task is to determine all non-empty possible subsequen...read more
Ans. 
Generate all possible subsequences of a given string.
• Use recursion to generate all possible subsequences by including or excluding each character in the string.

• Maintain a current index to keep track of the characters being considered.

• Append the current character to each subsequence generated so far.

• Recursively call the function with the next index to include the next character in subsequences.
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Round duration - 60 minutes
Round difficulty - Easy

This was a technical round where the interviewer asked me questions related to OS and Java.

Q1. What is the critical section problem?
Ans. 
The critical section problem is a synchronization issue in concurrent programming where multiple processes access shared resources.
• Critical section is a code segment that accesses shared resources and must be executed by only one process at a time.

• The goal is to prevent race conditions and ensure mutual exclusion.

• Solutions include using locks, semaphores, and mutex to control access to critical sections.

• Example: Multip...read more
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Q2. How can we create a thread in Java?
Ans. 
A thread in Java can be created by extending the Thread class or implementing the Runnable interface.
• Extend the Thread class and override the run() method

• Implement the Runnable interface and provide the implementation for the run() method

• Start the thread using the start() method
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Round duration - 30 minutes
Round difficulty - Easy

Typical HR round with behavioral questions.

Round duration - 60 minutes
Round difficulty - Medium

Technical round where the interviewer asked me questions based on data structures , algorithms and load balancer and session management.

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 use a hashmap to store the difference between the target sum and each element.

• Check if the difference exists in the hashmap, if so, add the pair to the result list.

• Sort the result list based on the criteria mentioned in the problem statement.
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Q2. 
Next Smallest Palindrome Problem Statement
Find the next smallest palindrome strictly greater than a given number 'N' represented as a string 'S'.
Explanation:
You are given a number in string format, a...read more
Ans. 
Find the next smallest palindrome greater than a given number represented as a string.
• Convert the string number to an integer for comparison.

• Increment the number until a palindrome greater than the input is found.

• Handle cases where the input is already a palindrome or has leading zeros.

• Return the next greater palindrome as a string.
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Round duration - 60 minutes
Round difficulty - Medium

Technical round where the interviewer asked me questions based on data structures , design patterns and php.

Q1. 
Check If Linked List Is Palindrome
Given a singly linked list of integers, determine if the linked list is a palindrome.
Explanation:
A linked list is considered a palindrome if it reads the same forwar...read more
Ans. 
Check if a given singly linked list of integers is a palindrome.
• Create a function to reverse the linked list.

• Use slow and fast pointers to find the middle of the linked list.

• Compare the first half of the linked list with the reversed second half to determine if it's a palindrome.
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Q2. Can you explain the implementation of the Singleton Design pattern?
Ans. 
Singleton Design pattern ensures a class has only one instance and provides a global point of access to it.
• Ensure the class has a private static instance variable.

• Provide a public static method to access the instance.

• Make the constructor private to prevent instantiation from outside the class.

• Lazy initialization can be used to create the instance only when needed.

• Thread safety considerations may be necessary in a multi
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Round duration - 60 minutes
Round difficulty - Medium

Technical round where the interviewer asked me questions based on Javascript, dbms, oops concepts and php.

Q1. Write a stored procedure to join two tables.
Ans. 
A stored procedure to join two tables in a database.
• Use the JOIN keyword to combine rows from two or more tables based on a related column between them.

• Specify the columns to be selected from each table in the SELECT statement.

• Use the ON keyword to specify the join condition.

• Consider using INNER JOIN, LEFT JOIN, RIGHT JOIN, or FULL JOIN based on the desired result.

• Test the stored procedure with sample data to ensure it
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Q2. What is the difference between an abstract class and an interface in Object-Oriented Programming?
Ans. 
Abstract class can have both abstract and non-abstract methods, while interface can only have abstract methods.
• Abstract class can have constructors, fields, and methods, while interface cannot have any implementation.

• A class can only extend one abstract class, but can implement multiple interfaces.

• Abstract classes are used to define common characteristics among subclasses, while interfaces are used to define a contract...read more
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Q3. How can you extract the domain name from a URL using jQuery?
Ans. 
Use jQuery to extract domain name from a URL
• Use the 'a' element to create a temporary link with the URL

• Access the 'hostname' property of the link to get the domain name

• Use regular expressions to extract the domain name from the URL
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Q4. What are closures in JavaScript?
Ans. 
Closures in JavaScript are functions that have access to variables from their outer scope even after the outer function has finished executing.
• Closures allow functions to access variables from their parent function even after the parent function has finished executing.

• They are created whenever a function is defined within another function.

• Closures are commonly used to create private variables and functions in JavaScrip...read more
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Round duration - 60 minutes
Round difficulty - Easy

In first round they asked me 2 coding questions where he asked me to code as close as possible to the actual one.

Q1. 
Ninja and Sorted Array Merging Problem
Ninja is tasked with merging two given sorted integer arrays ARR1 and ARR2 of sizes 'M' and 'N', respectively, such that the merged result is a single sorted array w...read more
Ans. 
Merge two sorted arrays into one sorted array in place.
• Use two pointers to compare elements from both arrays and place them in the correct position in ARR1.

• Start from the end of ARR1 and compare elements from both arrays, placing the larger element at the end of ARR1.

• Continue this process until all elements from ARR2 are merged into ARR1.
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Q2. 
Word Distance Calculation
Given a document represented as an array/list ARR of words with length N, find the smallest distance between two given words for multiple queries. The distance is defined as the ...read more
Ans. 
Find the smallest distance between two words in a document for multiple queries.
• Iterate through the document array to find the indices of the two words in each query.

• Calculate the absolute difference between the indices to get the distance.

• If a word from the query is not present in the document, return the length of the document array.

• Repeat the process for each query and output the smallest distance for each.
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Round duration - 60 minutes
Round difficulty - Easy

Then in the second round they asked a little about tree and told me to code 2 codes.

Q1. 
Level Order Traversal Problem Statement
Given a binary tree of integers, return the level order traversal of the binary tree.
Input:
The first line contains an integer 'T', representing the number of te...read more
Ans. 
The problem requires implementing a function to return the level order traversal of a binary tree.
• Implement a function that takes the root of the binary tree as input and returns the level order traversal of the tree.

• Use a queue data structure to perform level order traversal.

• Process each level of the tree one by one, starting from the root node.

• Print the node values at each level in the order they appear from left to ...read more
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Q2. 
Combination Sum Problem Statement
Given an array of distinct positive integers ARR and a non-negative integer 'B', find all unique combinations in the array where the sum is equal to 'B'. Numbers can be c...read more
Ans. 
Find all unique combinations in an array where the sum is equal to a given target sum, with elements in non-decreasing order.
• Use backtracking to generate all possible combinations.

• Sort the array to ensure elements are in non-decreasing order.

• Track the current combination and sum while backtracking.

• Terminate recursion when the sum equals the target sum.

• Avoid duplicates by skipping elements that have been used in previou
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Round duration - 30 minutes
Round difficulty - Easy

HR round with typical behavioral problems.

Round duration - 60 minutes
Round difficulty - Medium

This was a online test round where I was given 3 DSA questions to be solved in 60 minutes.

Q1. 
Count Ways to Reach the N-th Stair Problem Statement
You are provided with a number of stairs, and initially, you are located at the 0th stair. You need to reach the Nth stair, and you can climb one or tw...read more
Ans. 
The problem involves finding the number of distinct ways to climb to the Nth stair by taking one or two steps at a time.
• Use dynamic programming to solve the problem efficiently.

• The number of ways to reach the Nth stair is the sum of the number of ways to reach the (N-1)th stair and the (N-2)th stair.

• Handle base cases for N=0 and N=1 separately.

• Consider using modulo 10^9+7 to avoid overflow in calculations.
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Q2. 
Optimal Strategy for a Coin Game
You are playing a coin game with your friend Ninjax. There are N coins placed in a straight line.
Here are the rules of the game:
1. Each coin has a value associated wit...read more
Ans. 
The problem involves finding the optimal strategy to accumulate the maximum amount in a coin game with specific rules.
• Start by understanding the rules of the game and how players take turns to choose coins.

• Consider the scenario where both players play optimally to maximize winnings.

• Iterate through different strategies to determine the best approach for selecting coins.

• Keep track of the total winnings accumulated by eac...read more
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Q3. 
Generate All Parentheses Combinations
Given an integer N, your task is to create all possible valid parentheses configurations that are well-formed using N pairs. A sequence of parentheses is considered w...read more
Ans. 
Generate all possible valid parentheses configurations using N pairs.
• Use backtracking to generate all possible combinations of parentheses.

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

• Add '(' if there are remaining open parentheses, and add ')' if there are remaining close parentheses.

• Base case: when the length of the generated string is 2*N, add it to the result array.
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