30+ Interview Questions and Answers

The task is to determine if it is possible to select three nodes from a binary tree such that their sum equals a given value.

• Traverse the binary tree and store all the node values in an array

• Use three nested loops to iterate through all possible combinations of three nodes

• Check if the sum of the three nodes equals the given value

• If a valid combination is found, return True

• If no valid combination is found, return False

The task is to find the in-order traversal of a given binary tree.

• Implement a recursive function to perform in-order traversal of the binary tree

• Start from the left subtree, then visit the root, and finally visit the right subtree

• Use an array to store the values of the nodes in the in-order traversal

The task is to check whether a given binary tree is a complete binary tree or not.

• A complete binary tree is a binary tree where every level, except possibly the last, is completely filled.

• All nodes in the last level are placed at the left end.

• To check if a binary tree is complete, we can perform a level order traversal and check if any null nodes appear before all non-null nodes in the last level.

• If any null nodes appear before all non-null nodes in the last level, then the b...read more

The task is to find all possible paths for a rat to reach its destination in a maze.

• The maze is represented as a square matrix of 0s and 1s.

• The rat starts at (0, 0) and the destination is at (N-1, N-1).

• The rat can move in four directions: up, down, left, and right.

• Use backtracking to explore all possible paths.

• Print the paths in alphabetical order.

Program to store data in file block by block with 100 bytes per block and first 4 bytes for reading index and second 4 bytes for writing index.

• Use file handling functions to read and write data to file

• Use a loop to write data block by block

• Use a counter to keep track of block index

• Use bitwise operators to extract index from first 4 bytes

Use sockets to establish a connection between two systems and transfer the file using file I/O operations.

• Create a socket on the sender system using socket() function.

• Bind the socket to a port using bind() function.

• Establish a connection to the receiver system using connect() function.

• Open the file to be transferred using fopen() function.

• Read the file contents using fread() function.

• Send the file contents using send() function.

• Receive the file contents on the receiver system...read more

Path variable is used to locate executable files while classpath variable is used to locate Java classes.

• Path variable is used by the operating system to locate executable files.

• Classpath variable is used by Java to locate classes and resources.

• Path variable is system-specific while classpath variable is Java-specific.

• Path variable is set by the user while classpath variable is set by the developer.

• Example of path variable: C:\Windows\System32

• Example of classpath variable: C:...read more

Static and extern are storage classes in C/C++ with different functionalities.

• Static variables have a local scope but retain their value between function calls.

• Extern variables are declared outside a function and can be accessed by other files.

• Static functions can only be called within the same file they are declared in.

• Extern functions are declared in one file and can be used in other files.

• Static classes and functions are used to restrict access to certain parts of the code...read more

Yes, Java is completely object oriented.

• Java is designed to be completely object oriented.

• All code in Java is written inside classes and objects.

• Java supports encapsulation, inheritance, and polymorphism.

• Java does have some non-object oriented features like primitive data types.

• However, even these can be treated as objects using wrapper classes.

Half duplex allows communication in both directions, but only one direction at a time. Full duplex allows simultaneous communication in both directions.

• Half duplex is like a walkie-talkie where only one person can speak at a time.

• Full duplex is like a phone call where both parties can speak and listen at the same time.

• Examples of half duplex devices include Ethernet hubs and some two-way radios.

• Examples of full duplex devices include Ethernet switches and telephones.

C has four storage classes: auto, register, static, and extern.

• Auto: default storage class for local variables

• Register: stores variables in CPU registers for faster access

• Static: retains value between function calls

• Extern: used to access global variables across multiple files

Implementing a stack using arrays without custom data structures

• Use an array to store the elements of the stack

• Keep track of the top of the stack using a variable

• Implement push operation by adding elements to the end of the array

• Implement pop operation by removing elements from the end of the array

STL knowledge and finding loop in linked list

• STL (Standard Template Library) is a C++ library that provides containers, algorithms, and iterators.

• To find a loop in a linked list, we can use Floyd's cycle-finding algorithm.

• In this algorithm, we use two pointers, one moving at a slower pace and the other at a faster pace.

• If there is a loop in the linked list, the faster pointer will eventually catch up to the slower pointer.

• We can then reset one of the pointers to the head of t...read more

MySQL is a specific implementation of SQL, which is a standardized language for managing databases.

• MySQL is a specific relational database management system (RDBMS) that uses SQL as its query language.

• SQL (Structured Query Language) is a standardized language for managing databases, used by various RDBMS like MySQL, Oracle, and SQL Server.

• MySQL is open-source and free to use, while some other RDBMS like Oracle may require a license.

• MySQL has specific features like InnoDB stor...read more

Abstraction and interface are key concepts in Java for achieving abstraction and defining contracts for classes.

• Abstraction in Java is achieved using abstract classes and interfaces.

• Abstract classes can have both abstract and concrete methods, while interfaces can only have abstract methods.

• Interfaces define contracts that classes must implement, allowing for polymorphism and loose coupling.

• Example: interface Shape { void draw(); }

• Example: abstract class Animal { abstract voi...read more

Linkedlist add and delete node concept with code

• To add a node to a linked list, create a new node and update the next pointer of the current last node to point to the new node

• To delete a node from a linked list, update the next pointer of the previous node to skip over the node to be deleted

Exception is an event that occurs during the execution of a program and disrupts the normal flow of instructions.

• Exceptions are objects that are thrown at runtime when an abnormal condition occurs

• Java provides a set of predefined exceptions that can be used to handle errors

• Exceptions can be caught and handled using try-catch blocks

• Unchecked exceptions are those that are not checked at compile-time, while checked exceptions are checked at compile-time

A binary tree is a data structure where each node has at most two children.

• Consists of nodes, each with a left and right child pointer

• Root node is the topmost node

• Traversal methods include in-order, pre-order, and post-order

2 phase commit is a protocol used to ensure distributed transactions are either committed or rolled back.

• Used in distributed systems where multiple databases are involved in a transaction

• Ensures all databases either commit or rollback the transaction

• Involves a coordinator and multiple participants

• Coordinator sends a prepare message to participants, who respond with either commit or abort

• If all participants respond with commit, the coordinator sends a commit message

• If any part...read more

Serial protocol is a communication protocol used to transmit data between devices one bit at a time.

• Serial protocol is used in many applications such as RS-232, SPI, I2C, and USB.

• It is a simple and reliable way to transmit data over a long distance.

• Serial protocol can be synchronous or asynchronous.

• It is commonly used in embedded systems and communication between microcontrollers and sensors.

Deadlocks can be handled by using techniques like prevention, avoidance, detection, and recovery.

• Use prevention techniques like ensuring a strict ordering of resource requests to avoid circular wait.

• Implement avoidance techniques like ensuring that resources are only allocated if they can be used without causing a deadlock.

• Detect deadlocks by periodically checking for circular wait conditions and taking appropriate actions.

• Recover from deadlocks by aborting one or more proces...read more

Race condition is a situation in which the outcome of a program depends on the order of execution of its threads.

• Occurs when multiple threads access shared data and try to change it at the same time

• Can lead to unpredictable behavior and bugs in the program

• Prevented by using synchronization techniques like locks and semaphores

To balance a binary tree after deletion of a node, we can use rotations and reordering of nodes.

• Perform rotations to maintain balance factor of nodes

• Reorder nodes to ensure tree remains balanced

• Examples: AVL tree, Red-Black tree

Enum is a special data type in Java used to define a set of constants.

• Enums are used to represent a fixed number of values that do not change.

• They are declared using the enum keyword.

• Each enum constant is an object of the enum type.

• Enums can have constructors, methods, and fields.

• Example: enum Color { RED, GREEN, BLUE }

• Enums can also have values associated with them, like Color.RED(255, 0, 0).

Yes, I am able to handle work pressure.

• I prioritize tasks and manage my time effectively

• I communicate with my team and ask for help when needed

• I take breaks and practice stress-relieving techniques

• I stay organized and focused on the end goal

JSP stands for JavaServer Pages, a technology used for creating dynamic web pages.

• JSP allows embedding Java code in HTML pages

• It simplifies the process of creating dynamic web content

• JSP files are compiled into servlets by the server for execution