300+ Rohan Builders Interview Questions and Answers

Identify the duplicate integer in an array containing numbers between 1 and N-1.

• Iterate through the array and keep track of the frequency of each element using a hashmap.

• Return the element with a frequency greater than 1 as the duplicate integer.

• Time complexity can be optimized to O(N) using Floyd's Tortoise and Hare algorithm.

• Example: For input [1, 2, 3, 4, 4], the output should be 4.

Sort the individual digits of a 10 digit number.

• Convert the number to a string to access individual digits

• Use a sorting algorithm to sort the digits

• Convert the sorted digits back to a number

Demonstrate multilevel inheritance with classes GrandFather, Father, and Son with specific attributes and methods.

• Create a class GrandFather with a parameterized constructor and attribute grandFatherName.

• Create a class Father inheriting from GrandFather with an additional attribute fatherName.

• Create a class Son inheriting from Father with an additional attribute sonName and a method printName to display all names in a specific format.

• Ensure constructors initialize attributes ...read more

Reverse a singly linked list of integers and return the head of the reversed linked list.

• Iterate through the linked list and reverse the pointers to point to the previous node.

• Keep track of the current, previous, and next nodes while reversing the linked list.

• Update the head of the reversed linked list as the last node encountered during reversal.

Given start and end times of intervals, determine if any two intervals overlap.

• Iterate through intervals and check if any two intervals overlap by comparing their start and end times

• Sort intervals based on start times for efficient comparison

• Consider edge cases where intervals end and start at the same time

BFS traversal in a disconnected graph starting from vertex 0.

• Implement BFS algorithm to traverse the graph starting from vertex 0.

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

• Consider the bidirectional nature of edges in an undirected graph.

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

Given a string STR and a non-empty string PTR, find all starting indices of anagrams of PTR within STR.

• Create a frequency map of characters in PTR.

• Use sliding window technique to check anagrams in STR.

• Return the starting indices of anagrams found.

Find the Lowest Common Ancestor (LCA) of two nodes in a binary tree.

• Traverse the binary tree to find the paths from the root to nodes X and Y.

• Compare the paths to find the last common node, which is the LCA.

• Handle cases where one node is an ancestor of the other.

• Consider edge cases like when X or Y is the root node.

• Implement a recursive or iterative solution to find the LCA efficiently.

The task is to rearrange a given permutation of 'N' integers to form the lexicographically next greater permutation.

• Iterate from right to left to find the first element that is smaller than the element to its right.

• Swap this element with the smallest element to its right that is greater than it.

• Reverse the elements to the right of the swapped element to get the lexicographically next greater permutation.

Find the maximum elements for each subarray of size 'K' in an array of non-negative integers.

• Iterate through the array and maintain a deque to store the indices of elements in decreasing order.

• Pop elements from the deque if they are out of the current window of size 'K'.

• The front of the deque will always have the index of the maximum element in the current window.

Reverse a given string containing alphabets, numbers, and special characters.

• Iterate through the string from the end to the beginning and append each character to a new string.

• Use built-in functions like reverse() or StringBuilder in languages like Python or Java for efficient reversal.

• Handle special characters and numbers while reversing the string.

• Ensure to consider the constraints provided in the problem statement.

• Test your solution with different test cases to validate th...read more

When faced with an unsolvable problem, I break it down, research, seek help, experiment, and iterate until a solution is found.

• Break down the problem into smaller, manageable parts

• Research and gather information related to the problem

• Seek help from colleagues, online communities, or experts

• Experiment with different approaches or solutions

• Iterate and refine the solution based on feedback and results

Maximize the number of vaccines administered on a specific day while adhering to certain rules.

• Given n days, maxVaccines available, and a specific dayNumber, distribute vaccines to maximize on dayNumber

• Administer positive number of vaccines each day with a difference of 1 between consecutive days

• Ensure sum of vaccines distributed does not exceed maxVaccines

• Output the maximum number of vaccines administered on dayNumber for each test case

Find sum of all subsets in non-decreasing order of given array.

• Use recursion to generate all subsets of the array

• Calculate sum of each subset and store in a list

• Sort the list in non-decreasing order to get the final result

Find the length of the longest strictly increasing subsequence of heights of students in a row.

• Iterate through the heights array and for each element, find the length of the longest increasing subsequence ending at that element.

• Use dynamic programming to keep track of the longest increasing subsequence length for each element.

• Return the maximum length found as the result.

The task is to implement a function that returns the level order traversal of a binary tree given in level order.

• Create a queue to store nodes for level order traversal

• Start with the root node and enqueue it

• While the queue is not empty, dequeue a node, print its value, and enqueue its children

• Repeat until all nodes are traversed

Boundary traversal of a binary tree to find left boundary, right boundary, and leaf nodes in an anti-clockwise direction.

• Perform a pre-order traversal to get the left boundary nodes

• Perform an in-order traversal to get the leaf nodes

• Perform a post-order traversal to get the right boundary nodes

• Combine the results to get the boundary nodes in anti-clockwise direction

Return the middle node of a singly linked list, considering odd and even number of elements.

• Traverse the linked list with two pointers, one moving twice as fast as the other

• When the fast pointer reaches the end, the slow pointer will be at the middle

• Return the node pointed to by the slow pointer as the middle node

Arrange a string in zig-zag pattern with given number of rows and concatenate the rows.

• Iterate through the string and distribute characters to rows based on zig-zag pattern

• Concatenate the characters in each row to get the final result

• Handle edge cases like when number of rows is 1 or equal to the length of the string

A DBMS for managing college faculty, professors, courses, and students.

• The DBMS should have tables for faculty, professors, courses, and students.

• Each table should have appropriate attributes to store relevant information.

• Relationships can be established between tables using foreign keys.

• Queries can be used to retrieve information about faculty, professors, courses, and students.

• The DBMS can be used to track enrollment, grades, and other relevant data.

Find the length of the longest substring without repeating characters in a given string.

• Use a sliding window approach to keep track of the longest substring without repeating characters.

• Use a hashmap to store the index of each character as it appears in the string.

• Update the start index of the window when a repeating character is found.

• Calculate the maximum length of the substring as the window slides through the string.

The Floyd Warshall algorithm is used to find the shortest paths between all pairs of vertices in a graph, including graphs with negative edge weights.

• The algorithm works by considering all pairs of vertices and all intermediate vertices to find the shortest path.

• It can handle graphs with negative edge weights, but not negative weight cycles.

• The time complexity of the algorithm is O(N^3), where N is the number of vertices.

• Example: Given a graph with 4 vertices and 5 edges, fin...read more

Calculate the Nth Fibonacci number efficiently using recursion or dynamic programming.

• Implement a recursive function to calculate the Nth Fibonacci number.

• Use memoization to store previously calculated Fibonacci numbers for efficiency.

• Consider using dynamic programming to optimize the solution.

• Handle edge cases such as N = 1 or N = 2 separately.

• Ensure the solution works efficiently for large values of N (up to 10000).

Find the length of the longest substring with unique characters in a given string.

• Use a sliding window approach to keep track of the longest substring without repeating characters.

• Use a hashmap to store the index of each character in the string.

• Update the start index of the window when a repeating character is encountered.

• Calculate the maximum length of the window as you iterate through the string.

Print a binary pattern based on input integer N in a specific format.

• Iterate from 1 to N and print N - i + 1 numbers alternatively as 1 or 0 in each line

• Follow the pattern of increasing 1s and decreasing 0s in each line

• Handle the number of test cases and constraints as specified

Return all possible permutations of a given input string.

• Use recursion to generate all possible permutations of the input string.

• Swap characters at different positions to generate permutations.

• Handle duplicate characters in the input string by using a set to store unique permutations.

Identify all prime numbers less than or equal to a given positive integer N.

• Iterate from 2 to N and check if each number is prime

• Use the Sieve of Eratosthenes algorithm for efficient prime number identification

• Optimize by only checking up to the square root of N for divisors

Two people with torch cross, one returns, two faster people cross, one with torch returns, two slower people cross.

• Two slower people cross first (A and B), A returns with torch (1 minute)

• Two faster people cross (C and D), B returns with torch (2 minutes)

• Two slower people cross last (A and B) (10 minutes)

Count the number of subarrays whose combined strength matches the given enemy strength.

• Iterate through all subarrays and calculate their sum to check if it matches the enemy strength.

• Use two pointers technique to efficiently find subarrays with sum equal to the enemy strength.

• Consider edge cases like when the enemy strength is 0 or when all elements in the array are equal to the enemy strength.

Calculate and print the factorial of a given integer 'N'.

• Iterate from 1 to N and multiply each number to calculate factorial

• Handle edge cases like N=0 or N=1 separately

• Use recursion to calculate factorial efficiently

The code for finding the Lowest Common Ancestor (LCA) in a Binary Search Tree (BST).

• Start from the root node and compare it with the given two nodes.

• If both nodes are smaller than the current node, move to the left subtree.

• If both nodes are greater than the current node, move to the right subtree.

• If one node is smaller and the other is greater, then the current node is the LCA.

• Continue this process until the LCA is found.

Turn on one switch for a while, then turn it off and turn on another switch. One bulb will be on, one will be off, and one will be warm.

• Turn on switch 1 for a few minutes, then turn it off.

• Turn on switch 2 and enter the room with bulbs.

• The bulb that is on corresponds to switch 2, the warm bulb corresponds to switch 1, and the off bulb corresponds to switch 3.

Bubble Sort algorithm is used to sort an array of non-negative integers in non-decreasing order.

• Iterate through the array and compare adjacent elements, swapping them if they are in the wrong order.

• Repeat this process until the array is sorted.

• Time complexity of Bubble Sort is O(n^2) in worst case.

• Space complexity of Bubble Sort is O(1) as it is an in-place sorting algorithm.

Reverse a singly linked list iteratively and return the head of the reversed linked list.

• Iterate through the linked list and reverse the pointers to point to the previous node instead of the next node.

• Keep track of the previous, current, and next nodes while traversing the linked list.

• Update the head of the reversed linked list to be the last node encountered.

• Time complexity: O(N), Space complexity: O(1).

Design a parking lot with Logic Flow Diagram, E-R diagram, DB tables with relations, and commands for transactions.

• Identify the types of vehicles that will use the parking lot

• Determine the number of parking spaces needed for each vehicle type

• Create a flow diagram to show the process of entering and exiting the parking lot

• Design an E-R diagram to show the relationships between entities such as vehicles, parking spaces, and transactions

• Normalize the DB tables to reduce redundan...read more

Find uncommon characters in two strings and return them in lexicographically sorted order.

• Iterate through each character in both strings and keep track of their frequency using a hashmap.

• Iterate through the hashmap and add characters with frequency 1 to the result array.

• Sort the result array in lexicographical order and return it.

Given a node in a binary tree, find its inorder successor in the tree.

• Traverse the tree in in-order fashion to find the successor node.

• If the given node has a right child, the successor will be the leftmost node in the right subtree.

• If the given node does not have a right child, backtrack to the parent nodes to find the successor.

• Handle the case where the given node is the last node in the in-order traversal.

• Return the value of the successor node or 'NULL' if no successor exi...read more

Sort an array by moving all zeroes to the end.

• Iterate through the array and move all non-zero elements to the front.

• Count the number of zeroes encountered and append them at the end of the array.

• Use two pointers to swap elements and maintain the order.

The minimum number of attempts needed is 14.

• Start dropping the first egg from the 14th floor, then move up by one floor for each attempt until the first egg breaks.

• Once the first egg breaks, use the second egg to test each floor starting from the last unbroken floor.

• The worst-case scenario is dropping the first egg 14 times and the second egg 13 times, totaling 14 attempts.

Recursively remove consecutive duplicate characters from a string.

• Use recursion to check if the current character is the same as the next character, if so skip the next character

• Base case: if the string is empty or has only one character, return the string

• Example: Input: 'aaabcc', Output: 'abc'

WAP to generate a matrix from a given tree.

• Create a 2D array to store the matrix

• Traverse the tree and fill the matrix accordingly

• Use BFS or DFS to traverse the tree

• The matrix will be symmetric along the diagonal

Yes, this can be achieved by using a two-pointer approach to rearrange the array with negative numbers at the beginning.

• Use two pointers, one starting from the beginning and one from the end of the array.

• Swap elements at the two pointers if one is negative and the other is positive, and move the pointers accordingly.

• Continue this process until the two pointers meet in the middle of the array.

• The resulting array will have all negative numbers before positive numbers, with the ...read more

Find the sum of the largest and smallest elements in an array with the least number of comparisons.

• Iterate through the array to find the maximum and minimum elements.

• Keep track of the maximum and minimum elements as you iterate.

• After iterating, sum up the maximum and minimum elements.

• To achieve the task with the least number of comparisons, compare elements in pairs.

Function to check if a checkbox is checked in JavaScript

• Use the 'checked' property of the checkbox element

• Access the checkbox element using its ID or class name

• Return true if checked, false if not checked

Calculate total area covered by two overlapping rectangles on a 2-D plane.

• Calculate the area of each rectangle separately using the given coordinates.

• Find the overlapping region by determining the intersection of the two rectangles.

• Calculate the area of the overlapping region by multiplying its width and height.

• Add the areas of the two rectangles and subtract the area of the overlapping region to get the total area covered.

Move all zeroes to the end of an unsorted array while maintaining the order of non-zero elements.

• Iterate through the array and maintain two pointers - one for non-zero elements and one for zeroes.

• Swap non-zero elements with zeroes to move zeroes to the end of the array.

• Maintain the relative order of non-zero elements while moving zeroes to the end.

Swap two numbers without using a temporary variable.

• Use bitwise XOR operation to swap the values of X and Y without using a temporary variable.

• The XOR operation works by toggling the bits of the numbers.

• Example: X = 10, Y = 20. X = X XOR Y, Y = X XOR Y, X = X XOR Y. After swapping, X = 20, Y = 10.

Implement Merge Sort algorithm to sort a sequence of numbers in non-descending order.

• Divide the input array into two halves recursively until each array has only one element

• Merge the sorted halves to produce a completely sorted array

• Time complexity of Merge Sort is O(n log n)

• Example: Input: [3, 1, 4, 1, 5], Output: [1, 1, 3, 4, 5]

ACID properties are a set of properties that guarantee the reliability of transactions in database management systems.

• Atomicity ensures that either all operations in a transaction are completed successfully or none of them are. For example, transferring money from one account to another should either be completed in full or not at all.

• Consistency ensures that the database remains in a consistent state before and after the transaction. For example, if a transaction violates a ...read more

Make one horizontal cut through the middle of the cake, then make two vertical cuts perpendicular to each other.

• Make a horizontal cut through the middle of the cake to create two equal halves.

• Make one vertical cut through the center of one of the halves.

• Make another vertical cut through the center of the other half, perpendicular to the first cut.

• You will end up with 8 equal pieces of cake.

Yes, I can design an ER diagram for an online shopping portal.

• Entities: User, Product, Order, Payment, Cart

• Relationships: User places Order, Order contains Product, Payment for Order, User has Cart

• Attributes: User (id, name, email), Product (id, name, price), Order (id, date), Payment (id, amount)

DFS traversal to find connected components in an undirected and disconnected graph.

• Use Depth First Search (DFS) algorithm to traverse the graph and find connected components.

• Maintain a visited array to keep track of visited vertices.

• For each unvisited vertex, perform DFS to explore all connected vertices and form a connected component.

• Repeat the process until all vertices are visited and print the connected components.

Construct a binary tree from a given parent array and perform level-order traversal.

• Iterate through the parent array to create the binary tree using a queue data structure.

• Keep track of the parent-child relationships and construct the tree accordingly.

• Perform level-order traversal to print the nodes in the correct order.

Return the middle node of a singly linked list, considering odd and even number of nodes.

• Traverse the linked list with two pointers, one moving at twice the speed of the other

• When the faster pointer reaches the end, the slower pointer will be at the middle node

• Handle cases for odd and even number of nodes separately

• Return null if the list is empty

Return all prime numbers less than or equal to a given positive integer N.

• Iterate from 2 to N and check if each number is prime using a helper function.

• A number is prime if it is not divisible by any number from 2 to its square root.

• Store and return the prime numbers in an array in increasing order.

Determine the minimum number of platforms needed at a railway station so that no train has to wait.

• Sort the arrival and departure times arrays in ascending order.

• Use two pointers to iterate through the arrays and keep track of the number of platforms needed.

• Increment the number of platforms needed when a train arrives and decrement when a train departs.

• Return the maximum number of platforms needed at any point.

Create base class Shape with field shapeType and method printMyType. Implement Square and Rectangle classes with calculateArea method.

• Create a base class Shape with shapeType field and printMyType method.

• Implement Square and Rectangle classes inheriting from Shape.

• Include additional fields and methods in Square and Rectangle classes.

• Override printMyType method in Square and Rectangle classes to output their respective types.

• Ensure proper encapsulation and validation of length...read more

malloc() is used to dynamically allocate memory in C, while free() is used to release allocated memory.

• malloc() allocates a block of memory of specified size and returns a pointer to the beginning of the block.

• free() deallocates the memory previously allocated by malloc() or calloc().

• Example: int *ptr = (int*)malloc(5 * sizeof(int)); // Allocates memory for 5 integers

• Example: free(ptr); // Deallocates the memory allocated for the integers

Primary key uniquely identifies each record in a table, while unique key ensures that all values in a column are distinct.

• Primary key does not allow NULL values, while unique key allows one NULL value.

• A table can have only one primary key, but multiple unique keys.

• Primary key is automatically indexed, while unique key may or may not be indexed.

• Example: In a table of students, student ID can be a primary key as it uniquely identifies each student, while email address can be a ...read more

Java is platform-independent and uses automatic memory management, while C++ is faster and allows for more control over memory.

• Java is compiled to bytecode and runs on a virtual machine, while C++ is compiled to machine code.

• Java has automatic memory management through garbage collection, while C++ requires manual memory management.

• Java has a simpler syntax and is easier to learn, while C++ has more complex syntax and is more difficult to master.

• Java is used for web developme...read more

List is preferred when frequent insertion and deletion is required. Vector is preferred when random access is required.

• List is implemented as a doubly-linked list, allowing for efficient insertion and deletion at any position.

• Vector is implemented as a dynamic array, allowing for efficient random access.

• Use List when the number of elements is expected to change frequently and the order of elements matters less.

• Use Vector when the number of elements is fixed or changes infrequ...read more

Remove duplicates from an array while maintaining order.

• Use a set to keep track of unique elements.

• Iterate through the array and add elements to the set if not already present.

• Convert the set back to an array to maintain order.

Polymorphism can be achieved through method overloading, method overriding, and interfaces. Multiple inheritance can be solved using interfaces.

• Method overloading allows multiple methods with the same name but different parameters

• Method overriding allows a subclass to provide its own implementation of a method already defined in its superclass

• Interfaces provide a way to achieve multiple inheritance by allowing a class to implement multiple interfaces

• Diamond problem in multipl...read more

Polymorphism is the ability of an object to take on many forms. It allows objects of different classes to be treated as the same type.

• Polymorphism allows a single interface to be used for different types of objects.

• It enables code reusability and flexibility in object-oriented programming.

• For example, a parent class 'Animal' can have multiple child classes like 'Dog', 'Cat', and 'Bird'. They can all be treated as 'Animal' objects.

• Each child class can have its own implementati...read more

Query to find player with maximum runs in a match on given date and venue

• Use MAX() function to find maximum runs

• Join tables for player name, match details and runs scored

• Filter by given date and venue

• Order by runs scored and limit to 1 result

Polymorphism refers to the ability of an object to take on many forms. The diamond problem occurs in multiple inheritance.

• Polymorphism can be achieved through method overloading and method overriding.

• Method overloading allows multiple methods with the same name but different parameters.

• Method overriding occurs when a subclass provides a specific implementation of a method already defined in its superclass.

• The diamond problem arises in languages that support multiple inheritan...read more

Operator overloading in OOP allows custom behavior for operators like +, -, *, etc.

• Operator overloading is a feature in OOP that allows defining custom behavior for operators

• Example: Overloading the + operator to concatenate strings or add two numbers

• Example: Overloading the * operator to perform matrix multiplication

BCNF is a normal form in database management systems that ensures all determinants are candidate keys.

• BCNF stands for Boyce-Codd Normal Form.

• It is a stricter version of 3NF (Third Normal Form).

• In BCNF, every determinant must be a candidate key.

• It helps in reducing redundancy and anomalies in the database.

• Example: If a table has columns A, B, and C, and A determines B and B determines C, then it is not in BCNF unless A is a candidate key.

Use two identical wires to measure 45 minutes by burning them at different ends.

• Burn one end of the first wire and both ends of the second wire simultaneously.

• When the first wire burns out completely (30 minutes), light the other end of the second wire.

• When the second wire burns out completely (15 minutes), 45 minutes have passed.

By burning one candle at both ends, you can calculate 45 minutes using only 2 candles.

• Light one end of the first candle and both ends of the second candle simultaneously.

• When the second candle burns out completely, 30 minutes have passed.

• Light the other end of the first candle and let it burn. When it meets the first end, 15 minutes have passed.

To handle a team, identify areas of improvement for each team member and get approval from the Director.

• Regularly communicate with team members to understand their strengths and weaknesses.

• Provide constructive feedback and coaching to help team members improve.

• Set clear goals and expectations for each team member.

• Encourage collaboration and teamwork within the team.

• Get approval from the Director before implementing any major changes or improvements.

Foreign key is a column in a table that refers to the primary key of another table.

• It establishes a relationship between two tables.

• It ensures referential integrity.

• It can be null, but only if it is defined as nullable.

• It helps in joining tables.

• Example: Customer table has a foreign key to the Order table's primary key.

• Example: Order table's foreign key can be null if the order has not been placed by any customer yet.

Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity.

• Normalization involves breaking down a database into smaller, more manageable tables.

• It helps to eliminate data redundancy and inconsistencies.

• Normalization ensures that each table has a primary key and that data is stored in a logical and consistent manner.

• It improves data integrity and reduces the likelihood of errors and inconsistencies.

• Normalization is important f...read more

The database design for an ATM system should include tables for users, accounts, transactions, and ATM machines.

• Create a table for users with fields like user_id, name, pin, etc.

• Create a table for accounts with fields like account_id, user_id, balance, etc.

• Create a table for transactions with fields like transaction_id, account_id, amount, date, etc.

• Create a table for ATM machines with fields like atm_id, location, status, etc.

AES is a more secure and efficient cipher compared to DES.

• AES has a block size of 128 bits, while DES has a block size of 64 bits.

• AES supports key sizes of 128, 192, or 256 bits, while DES supports only 56-bit keys.

• AES is considered more secure and efficient than DES due to its stronger encryption algorithm and larger key sizes.

Normalized form is better for data consistency and scalability.

• Normalized form reduces data redundancy and ensures data consistency.

• Normalized form allows for easier scalability and maintenance.

• Single table/2 tables may be appropriate for small, simple datasets.

• Normalized form may require more complex queries to retrieve data.

• Normalized form may require more storage space due to additional tables.

• Example: Normalized form for a customer database would have separate tables for ...read more

Linux is an open-source operating system known for its stability, security, and flexibility.

• Linux is a Unix-like operating system that was developed as a free and open-source software.

• It provides a stable and secure environment for running applications and services.

• Linux supports a wide range of hardware architectures and has a large community of developers and users.

• It offers a command-line interface, as well as various graphical user interfaces.

• Linux is highly customizable ...read more

Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity.

• Normalization involves breaking down a database into smaller, more manageable tables.

• It helps in reducing data redundancy by storing data in a structured way.

• There are different normal forms such as 1NF, 2NF, 3NF, BCNF, etc., each with specific rules to follow.

• Normalization ensures data integrity and reduces the chances of anomalies like insertion, update, and deletio...read more

Public cloud is shared infrastructure available to anyone, while private cloud is dedicated infrastructure for a single organization.

• Public cloud is accessible to multiple organizations or users, while private cloud is exclusive to a single organization.

• Public cloud services are provided over the internet, while private cloud services can be hosted on-premises or in a dedicated data center.

• Public cloud offers cost-effective scalability and flexibility, while private cloud off...read more

The shortest time needed for all four people to cross the bridge is 17 minutes.

• First, the 1 min and 2 min person cross the bridge (2 mins).

• Then, the 1 min person goes back with the torch (1 min).

• Next, the 7 min and 10 min person cross the bridge (10 mins).

• Finally, the 2 min person goes back with the torch (2 mins).

• Total time taken: 2 + 1 + 10 + 2 = 17 minutes.

I am confident in developing arrays, linked lists, and hash tables.

• Arrays are simple and efficient for storing and accessing data.

• Linked lists are useful for dynamic data structures and efficient insertion/deletion.

• Hash tables provide fast access to data with key-value pairs.

Linux Shell is a command-line interpreter that allows users to interact with the operating system. There are various types of shells in Linux.

• Linux Shell is a program that interprets user commands and executes them.

• It provides a command-line interface for users to interact with the Linux operating system.

• Shells can be used to run scripts, automate tasks, and manage system resources.

• Some popular shells in Linux are Bash (Bourne Again SHell), C Shell (csh), Korn Shell (ksh), an...read more

String class is immutable in Java to ensure security, thread-safety, and performance.

• Immutable objects are thread-safe as they cannot be modified by multiple threads simultaneously.

• Immutable objects are also secure as they cannot be modified by malicious code.

• String pool is possible because of immutability, which improves performance by reducing memory usage.

• StringBuffer and StringBuilder classes are used for mutable string operations.

Find the minimum and maximum values in an array in a single traversal.

• Initialize min and max variables with the first element of the array

• Iterate through the array and update min and max if a smaller or larger value is found

• Return the min and max values

C++ is a programming language. Deep copy creates a new object and copies all values, while shallow copy creates a reference to the original object.

• C++ is a general-purpose programming language

• Deep copy creates a new object with its own copy of the data

• Shallow copy creates a reference to the original object

• Deep copy is safer but can be slower and consume more memory

• Shallow copy is faster but can lead to unexpected behavior if the original object is modified

C is a procedural programming language while C++ is a multi-paradigm programming language with object-oriented features.

• C is a procedural programming language while C++ supports both procedural and object-oriented programming.

• C does not support classes and objects while C++ does.

• C does not have built-in support for exception handling while C++ does.

• C does not have namespaces while C++ does.

• C does not have function overloading while C++ does.

C is a procedural programming language while C++ is an object-oriented programming language with features like classes and inheritance.

• C is a procedural programming language, while C++ is a multi-paradigm language with support for object-oriented programming.

• C does not support classes and objects, while C++ does.

• C uses structures for data organization, while C++ uses classes.

• C does not have features like inheritance and polymorphism, which are present in C++.

• C++ allows functi...read more

The 'finally' block in Java is used to execute code after try-catch blocks, even if an exception is thrown.

• The 'finally' block is always executed, regardless of whether an exception is thrown or caught.

• It is used to release resources like database connections, network connections, etc.

• If the JVM exits while the try or catch code is being executed, then the 'finally' block may not execute.

• If the thread executing the try or catch code is interrupted or killed, the 'finally' blo...read more

Count pairs of numbers where ending digit of ith number equals starting digit of jth number.

• Iterate through each pair of numbers in the list

• Check if the ending digit of the ith number equals the starting digit of the jth number

• Increment the count if the condition is met

Various SQL queries related to data manipulation and retrieval were asked during the interview.

• Basic SELECT queries to retrieve data from a single table

• JOIN queries to retrieve data from multiple tables based on a common column

• Aggregate functions like COUNT, SUM, AVG, etc. to perform calculations on data

• Subqueries to retrieve data based on the result of another query

• UPDATE queries to modify existing data in a table

• DELETE queries to remove specific records from a table

Given a chessboard, find the maximum number of squares present.

• Start with the smallest square and count all possible squares

• Use the formula n*(n+1)*(2n+1)/6 to find the total number of squares in an n x n chessboard

• Add up the squares of all sizes from 1 to n to get the maximum number of squares

• For example, an 8 x 8 chessboard has 204 squares

The program should differentiate between integers and characters when using the assignment operator (=).

• Check the data type of the variable before assigning a value.

• Use conditional statements to perform different actions based on the data type.

• For integers, assign the value directly. For characters, convert the character to its ASCII value and assign it.

Yes, a unique key can be a primary key.

• A primary key is a unique identifier for a record in a table.

• A unique key is a constraint that ensures the values in a column are unique.

• A unique key can be used as a primary key if it meets the requirements.

• A primary key cannot have NULL values, while a unique key can have one NULL value.

Write-ahead logging is a technique used in DBMS to ensure that changes are recorded in the log before they are applied to the database.

• Write-ahead logging ensures that changes are first written to the log file before being applied to the database to maintain data integrity.

• It helps in recovering the database in case of a system crash or failure by replaying the log entries to bring the database back to a consistent state.

• This technique is commonly used in databases like Postg...read more

Implementing a queue using stack involves using two stacks to simulate the behavior of a queue.

• Create two stacks, one for enqueue and one for dequeue operations.

• For enqueue operation, push the element onto the enqueue stack.

• For dequeue operation, if the dequeue stack is empty, pop all elements from the enqueue stack and push onto the dequeue stack.

• Pop the top element from the dequeue stack for dequeue operation.

I would use load balancing, caching, and scaling techniques to manage the 1 million requests.

• Implement load balancing to distribute requests evenly across multiple servers.

• Utilize caching to store frequently accessed data and reduce response times.

• Scale horizontally by adding more servers to handle the increased load.

• Optimize code and database queries to improve performance.

• Monitor system performance and make adjustments as needed.