100+ Namo Auto Agencies Interview Questions and Answers

To measure 4L of water using 3L and 5L jars, fill the 5L jar, pour 3L into the 3L jar, empty the 3L jar, and pour the remaining 2L from the 5L jar into the 3L jar. Finally, fill the 5L jar again and pour 1L into the 3L jar. Now, the 5L jar contains 4L of water.

• Fill the 5L jar completely

• Pour 3L from the 5L jar into the 3L jar

• Empty the 3L jar

• Pour the remaining 2L from the 5L jar into the 3L jar

• Fill the 5L jar again

• Pour 1L from the 5L jar into the 3L jar

Singleton class is a class that can only have one instance at a time.

• It is used to control access to a shared resource or limit the instantiation of a class to one object.

• To make a class singleton, make the constructor private and provide a static method to get the instance.

• Example: public class Singleton { private static Singleton instance = new Singleton(); private Singleton() {} public static Singleton getInstance() { return instance; } }

Challenges faced in RPA experience and how resolved

• One challenge was automating a process with multiple decision points, resolved by creating a decision tree

• Another challenge was handling exceptions, resolved by implementing exception handling mechanisms

• Integration with legacy systems was a challenge, resolved by creating custom connectors

• Lack of standardization in input data was a challenge, resolved by implementing data validation and cleansing mechanisms

vptr stands for virtual pointer and vptr table is a table of function pointers used in polymorphism in C++.

• vptr is a hidden member variable in C++ objects that points to the vptr table.

• vptr table is a table of function pointers that maps virtual functions to their addresses.

• Each object of a class with virtual functions has its own vptr and shares the same vptr table with other objects of the same class.

• vptr and vptr table are created when an object of a class with virtual fun...read more

Serialization is the process of converting an object into a stream of bytes, while deserialization is the reverse process.

• Serialization is used for data storage, transmission, and object persistence.

• Deserialization is used to recreate the original object from the serialized data.

• Examples of serialization formats include JSON, XML, and binary formats like Protocol Buffers and Apache Avro.

• Serialization can also be used for deep copying objects.

• Deserialization can be vulnerable ...read more

Program to find duplicate elements in arraylist with minimum iterations

• Use HashSet to store unique elements and ArrayList to store duplicates

• Iterate through the ArrayList only once

• Use contains() method to check if element is already in HashSet

Weigh 3 groups of 3 balls each, then weigh 2 heaviest balls from the heaviest group to find the heaviest ball.

• Divide the 9 balls into 3 groups of 3 balls each.

• Weigh the first 2 groups against each other.

• If one group is heavier, weigh 2 balls from that group against each other to find the heaviest ball.

• If both groups weigh the same, weigh the third group to find the heaviest group.

• Weigh 2 heaviest balls from the heaviest group to find the heaviest ball.

Answering coding questions on string reversal, variable swapping, and pattern printing.

• For string reversal, use a loop to iterate through the string and append each character to a new string in reverse order.

• To separate vowels and consonants, use a loop to iterate through the string and check if each character is a vowel or consonant.

• To swap two variables without a third variable, use arithmetic operations or XOR bitwise operator.

• For pattern printing, use nested loops to prin...read more

Const reference in copy constructor is used to avoid unnecessary object copying and improve performance.

• Const reference allows us to pass objects by reference without modifying them.

• Using const reference in copy constructor avoids creating a temporary copy of the object being passed.

• It helps in preventing unnecessary memory allocation and improves performance.

• Const reference ensures that the original object is not modified during the copy construction process.

Program to display a pattern of numbers in a pyramid shape.

• Use nested loops to print the numbers in the desired pattern.

• The outer loop controls the number of rows and the inner loop prints the numbers in each row.

• Use a variable to keep track of the number to be printed in each row.

• Print a new line after each row is printed.

Swapping of numbers can be done using call by value, address and reference.

• Call by value: Pass the values of variables as arguments to the function. Swap the values inside the function.

• Call by address: Pass the addresses of variables as arguments to the function. Swap the values using pointers inside the function.

• Call by reference: Pass the references of variables as arguments to the function. Swap the values using references inside the function.

To create a backup table in MySQL, use the CREATE TABLE statement with SELECT INTO.

• Use the CREATE TABLE statement with SELECT INTO to create a backup table.

• Specify the name of the backup table and the name of the original table.

• Use the SELECT INTO statement to copy the data from the original table to the backup table.

• Example: CREATE TABLE backup_table SELECT * FROM original_table;

• Make sure to regularly update the backup table to ensure data consistency.

OOPs concepts include Encapsulation, Inheritance, Abstraction, and Polymorphism.

• Encapsulation: bundling of data and methods that operate on that data

• Inheritance: creating new classes from existing ones

• Abstraction: hiding implementation details and showing only necessary information

• Polymorphism: ability of objects to take on multiple forms or behaviors

CSS position properties are used to position elements on a web page.

• The position property specifies the type of positioning method used for an element.

• The top, bottom, left, and right properties are used to position the element.

• The static, relative, absolute, fixed, and sticky values are used for the position property.

• Static is the default value and elements are positioned according to the normal flow of the page.

• Relative positions the element relative to its normal position....read more

Key concepts of OOP include encapsulation, inheritance, polymorphism, and abstraction.

• Encapsulation: Bundling data and methods that operate on the data into a single unit (object).

• Inheritance: Allowing a class to inherit properties and behavior from another class.

• Polymorphism: Objects of different classes can be treated as objects of a common superclass.

• Abstraction: Hiding complex implementation details and showing only the necessary features to the outside world.

HashMap is a data structure that stores key-value pairs and uses hashing to quickly retrieve values based on keys.

• HashMap internally uses an array of linked lists to store key-value pairs.

• When a key-value pair is added, the key is hashed to determine the index in the array where the pair will be stored.

• If multiple keys hash to the same index (collision), a linked list is used to store these pairs.

• To retrieve a value, the key is hashed again to find the index and then the link...read more

A multi-threading program to print 1 2 1 2 using 2 threads.

• Create two threads and pass a flag to each thread to print either 1 or 2.

• Use a synchronization mechanism like mutex or semaphore to ensure alternate printing.

• Join the threads to wait for their completion.

Multithreading is the ability of a CPU to execute multiple threads concurrently. POSIX thread is a standard for thread creation and management.

• Multithreading allows multiple threads to run concurrently, improving performance and responsiveness.

• POSIX thread (pthread) is a standard for creating and managing threads in Unix-based systems.

• Thread synchronization is the coordination of threads to ensure that they do not interfere with each other's execution.

• Mutexes, semaphores, and...read more

Garbage collector in Java is an automatic memory management system that frees up memory by removing unused objects.

• Garbage collector runs in the background and identifies objects that are no longer in use

• It frees up memory by removing those unused objects

• It helps prevent memory leaks and improves performance

• Java provides different types of garbage collectors such as Serial, Parallel, CMS, and G1

• Example: If an object is created but not used anymore, the garbage collector will ...read more

Volatile keyword is used to indicate that a variable's value can be changed unexpectedly.

• It is used in multi-threaded programming to ensure that the value of a variable is always up-to-date and consistent across all threads.

• It prevents the compiler from optimizing code that accesses the variable, ensuring that the variable is always read from memory and not from a cache.

• Examples include hardware registers, shared memory, and global variables that can be accessed by multiple t...read more

Program to reverse a string in any language

• Create an empty string variable to store the reversed string

• Loop through the original string from the end to the beginning

• Append each character to the empty string variable

• Return the reversed string

Interfaces in software development define a contract for classes to implement certain methods or properties.

• Interfaces in programming are like blueprints that define the structure of a class.

• Classes that implement an interface must provide definitions for all the methods and properties specified in the interface.

• Interfaces allow for polymorphism and code reusability.

• Example: An interface 'Shape' may have methods like 'calculateArea' and 'calculatePerimeter', which classes lik...read more

Different types of joins in SQL include inner join, left join, right join, and full outer join.

• Inner join: Returns rows when there is a match in both tables.

• Left join: Returns all rows from the left table and the matched rows from the right table.

• Right join: Returns all rows from the right table and the matched rows from the left table.

• Full outer join: Returns rows when there is a match in either table.

Views in SQL are virtual tables that display data from one or more tables.

• Views are created using SELECT statements.

• They can be used to simplify complex queries.

• They can also be used to restrict access to sensitive data.

• Views do not store data themselves, but rather display data from other tables.

• Example: CREATE VIEW myView AS SELECT * FROM myTable WHERE column = 'value';

Null pointer points to nothing, while dangling pointer points to memory that has been deallocated.

• Null pointer is a pointer that does not point to any memory location.

• Dangling pointer is a pointer that points to memory that has been deallocated.

• Accessing a null pointer will result in a segmentation fault.

• Accessing a dangling pointer can lead to unpredictable behavior or crashes.

• Example: int* nullPtr = nullptr; int* danglingPtr = new int; delete danglingPtr; danglingPtr = null...read more

My expected CTC would depend on the job role, company size, location, and benefits package.

• Consider the job role and responsibilities when determining expected CTC.

• Research industry standards and average salaries for similar positions.

• Factor in the company size and location, as cost of living varies.

• Take into account additional benefits such as healthcare, retirement plans, and bonuses.

• Be prepared to negotiate based on your skills, experience, and market demand.

Constructor is used to initialize an object while method is used to perform an action on an object.

• Constructor is called automatically when an object is created while method is called explicitly.

• Constructor has the same name as the class while method has a unique name.

• Constructor does not have a return type while method has a return type.

• Example of constructor: public class Car { public Car() { //initialize variables } }

• Example of method: public void startEngine() { //perform...read more

Program to reverse a string in minimum iteration

• Use two pointers, one at the start and one at the end of the string

• Swap the characters at the two pointers and move the pointers towards each other

• Repeat until the pointers meet in the middle of the string

Process is a program in execution. Synchronization is the coordination of multiple processes or threads.

• Process is a program in execution that has its own memory space and resources.

• Synchronization is the coordination of multiple processes or threads to ensure they do not interfere with each other.

• Synchronization can be achieved through various mechanisms such as locks, semaphores, and monitors.

• Examples of synchronization include ensuring only one thread accesses a shared res...read more

Spring MVC follows a Model-View-Controller architecture pattern for building web applications.

• Spring MVC separates the application into three main components: Model, View, and Controller.

• Model represents the data of the application and the business logic to manipulate the data.

• View is responsible for rendering the data to the user interface.

• Controller handles the user input, processes it, and interacts with the Model and View.

• Spring MVC uses DispatcherServlet as the front con...read more

Design class diagram for Flower shop

• Create a Flower class with attributes like name, color, price, etc.

• Create a Bouquet class that has a list of Flower objects

• Create a Customer class with attributes like name, address, phone number, etc.

• Create an Order class that has a Customer object and a Bouquet object

• Create a Payment class with attributes like payment method, amount, etc.

• Create a Delivery class with attributes like delivery address, delivery date, etc.

Program to reverse a linked list

• Create a new empty linked list

• Traverse the original linked list and insert each node at the beginning of the new list

• Return the new reversed linked list

Smart pointers are objects that manage the lifetime of dynamically allocated memory in C++.

• Smart pointers automatically deallocate memory when it is no longer needed.

• They prevent memory leaks and dangling pointers.

• Examples of smart pointers in C++ are unique_ptr, shared_ptr, and weak_ptr.

Redux is a state management library for JavaScript applications.

• Redux uses a single source of truth called the store to manage the application state.

• Reducers are pure functions that specify how the state should change based on the actions dispatched.

• Actions are plain JavaScript objects that describe the type of change to be made to the state.

• When an action is dispatched, the store passes the current state and the action to the reducer, which returns the new state.

• Redux follow...read more

Annotations in Java are used to provide metadata about a program, which can be used by the compiler or at runtime.

• 1. @Override - Indicates that a method overrides a method in its superclass.

• 2. @Deprecated - Marks a method as deprecated, meaning it should no longer be used.

• 3. @SuppressWarnings - Suppresses compiler warnings for a given part of the code.

Code to find next smallest palindrome.

• Iterate from middle to left and right, incrementing/decrementing digits to create palindrome

• Handle edge cases like all 9s in number

• Check if number is palindrome or not

Code for binary search algorithm

• Binary search is a divide and conquer algorithm

• It works by repeatedly dividing the search interval in half

• If the value is found, return the index. Else, repeat on the appropriate half

• The array must be sorted beforehand

StringBuffer is synchronized and thread-safe, while StringBuilder is not synchronized.

• StringBuffer is slower due to synchronization, while StringBuilder is faster.

• StringBuffer is preferred in multithreaded environments, while StringBuilder is preferred in single-threaded environments.

• Example: StringBuffer sb = new StringBuffer(); StringBuilder sb = new StringBuilder();

Mutex is a synchronization object used to prevent multiple threads from accessing shared resources simultaneously.

• Mutex stands for mutual exclusion.

• It is used to protect shared resources from race conditions.

• Mutex provides exclusive access to a shared resource.

• Syntax: pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

• Example: pthread_mutex_lock(&mutex); // acquire lock

• pthread_mutex_unlock(&mutex); // release lock

A bug is an error, flaw, failure, or fault in a computer program or system. Unit testing is a software testing method where individual units or components of a software are tested in isolation.

• Bug is an error, flaw, failure, or fault in a computer program or system.

• Unit testing is a software testing method where individual units or components of a software are tested in isolation.

• Bug testing helps identify and fix issues in the software.

• Unit testing ensures that each unit of ...read more

Synchronization is used to ensure consistency and avoid conflicts in real-time systems.

• Real-time systems require synchronization to ensure that data is consistent and up-to-date across multiple devices or processes.

• Synchronization can be achieved through various techniques such as locks, semaphores, and message passing.

• Examples of real-time systems that use synchronization include stock trading platforms, online gaming, and traffic control systems.

SDLC stands for Software Development Life Cycle. It is a process used by software developers to design, develop, and test software.

• SDLC is a systematic process for building software applications.

• There are different types of SDLC models such as Waterfall, Agile, Iterative, Spiral, etc.

• Each type of SDLC model has its own set of advantages and disadvantages.

• SDLC involves phases like planning, analysis, design, implementation, testing, and maintenance.

• Example: Waterfall model fol...read more

A dangling pointer is a pointer that points to a memory location that has been deallocated, leading to potential crashes or undefined behavior.

• Dangling pointers can occur when memory is freed but the pointer is not set to NULL.

• Accessing a dangling pointer can result in accessing invalid memory.

• Example: int* ptr = new int; delete ptr; // ptr is now a dangling pointer

Design patterns are reusable solutions to common software problems.

• Creational patterns: Singleton, Factory, Abstract Factory

• Structural patterns: Adapter, Decorator, Facade

• Behavioral patterns: Observer, Strategy, Command

• Examples: MVC, Dependency Injection, Template Method

Reversing the nodes in a linked list involves changing the direction of pointers to go from the end to the beginning.

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

• Use three pointers - prev, current, and next - to keep track of the nodes while reversing the list.

• Update the head of the linked list to point to the last node after reversing.

Multithreading and data structures are important concepts in Java programming.

• Multithreading allows for concurrent execution of multiple threads within a single program.

• Data structures are used to organize and manipulate data efficiently.

• Examples of data structures include arrays, linked lists, stacks, and queues.

• Java provides built-in support for multithreading through the Thread class and the Runnable interface.

• Synchronization is important in multithreading to prevent race ...read more

OOPs concepts include encapsulation, inheritance, polymorphism, and abstraction in code.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Inheritance: Allowing a new class to inherit properties and behavior from an existing class.

• Polymorphism: Objects of different classes can be treated as objects of a common superclass.

• Abstraction: Hiding the implementation details and showing only the necessary features of an object.

A singleton class is a class that can only be instantiated once.

• Ensure the constructor is private

• Provide a static method to access the instance

• Lazy initialization can be used to defer object creation

• Thread safety should be considered

Program to reverse a linked list

• Traverse the linked list and change the direction of pointers

• Use three pointers to keep track of current, previous and next nodes

• Handle edge cases like empty list or list with only one node

Perform CRUD operations on a JSON object

• Use POST method to create new data

• Use GET method to read data

• Use PUT method to update data

• Use DELETE method to delete data

Reverse a given string

• Use a loop to iterate through the string and append each character to a new string in reverse order

• Alternatively, use built-in string functions like reverse() or slice()

• Remember to handle edge cases like empty strings or strings with only one character

Spring Boot is a Java-based framework used for creating standalone, production-grade Spring-based Applications.

• Spring Boot simplifies the process of creating Spring applications by providing a set of default configurations.

• It allows developers to quickly set up and run standalone Spring applications with minimal configuration.

• Spring Boot includes embedded servers like Tomcat, Jetty, or Undertow, making it easy to deploy applications.

• It promotes convention over configuration, ...read more

Inheritance is a concept in object-oriented programming where a class inherits properties and behaviors from another class.

• Allows a class to inherit attributes and methods from another class

• Promotes code reusability and reduces redundancy

• Creates a parent-child relationship between classes

• Derived class can override or extend the functionality of the base class

• Example: Class 'Car' can inherit from class 'Vehicle' and inherit properties like 'speed' and methods like 'drive()'

No, they are not equal because they are two separate instances of arrays.

• Empty arrays are two separate instances, so they are not strictly equal.

• Comparing two empty arrays with strict equality will return false.

Designing a linked list involves creating a data structure where each element points to the next one.

• Define a Node class with a value and a next pointer

• Create a LinkedList class with a head pointer

• Implement methods to add, remove, and traverse nodes

• Consider edge cases like adding to an empty list or removing the head node