SDE - 1

The four fundamental principles of object-oriented programming are encapsulation, inheritance, polymorphism, and abstraction. Encapsulation refers to the practice of hiding the implementation details of an object and exposing only the necessary information through its interface. Inheritance allows a new class to inherit the properties and methods of an existing class, thus promoting code reuse. Polymorphism enables objects of different classes to be used interchangeably, while abstraction refers to the practice of representing complex systems by hiding unnecessary details and exposing only the essential features.

A DBMS (Database Management System) is a software system that is designed to manage and organize large collections of data. The main functions of a DBMS include:

Data storage: The DBMS stores data in a structured format and allows for efficient retrieval and manipulation of the data.

Data security: The DBMS provides various security features such as user authentication, data encryption, and access control to protect the data from unauthorized access.

Data integrity: The DBMS ensures that the data stored in the database is accurate, consistent, and complete.

Data recovery: The DBMS provides tools to recover the data in case of any unexpected failures such as power outages or hardware crashes.

Data concurrency control: The DBMS manages concurrent access to the data by multiple users, ensuring that the data remains consistent even when multiple users are modifying it simultaneously.

Data modeling and design: The DBMS helps to design, create and define the structure of the data, relationships and constraints.

Data querying and reporting: The DBMS provides a user-friendly interface for querying and reporting the data stored in the database.

The purpose of system design is to translate the requirements of a system into a detailed blueprint that can be used to guide the construction of the system. The key steps involved in the process of system design are:

Define the problem: Understand and clearly define the problem that the system is intended to solve, and identify the requirements for the system.

Analyze the requirements: Break down the requirements into smaller, more manageable parts, and identify any constraints that may affect the design of the system.

Develop a high-level design: Create a high-level design that outlines the overall structure and components of the system, and how they will interact with each other.

Create a detailed design: Develop a detailed design that includes the specific components and interfaces that will be used to implement the system, as well as the algorithms and data structures that will be used to solve the problem.

Verify the design: Verify that the design meets all the requirements and constraints and that it is feasible to implement.

Refine the design: Make any necessary changes and improvements to the design, and ensure that it is ready for implementation.

Document the design: Document the design in a way that is easily understandable by all stakeholders, including developers, testers, and users.

Overall, the key steps involve in system design are understanding the problem, gathering the requirements, analyzing them, creating a high-level and detailed design, verify it, refine it and document it.

The main functions of an operating system (OS) include:

Resource management: The OS manages and allocates system resources such as memory, processing power, and storage to different programs and processes running on the computer.

Memory management: The OS manages the computer's memory and ensures that each process has the necessary resources to run efficiently.
Process management: The OS creates, schedules, and manages the execution of different processes and programs on the computer.

Security: The OS provides various security features such as user authentication, access control, and data encryption to protect the computer and its resources from unauthorized access.

File management: The OS manages the file system and provides a hierarchical structure for organizing and accessing files and directories.

Input/Output management: The OS manages the input and output operations of the computer, such as managing keyboard and mouse input, and managing the display of information on the screen.

Networking: The OS provides the necessary functions and protocols for the computer to connect and communicate with other devices on a network.

Virtualization: The OS manages the virtualization of the computer's resources, allowing multiple virtual machines to run on a single physical machine.

1st weigh: Divide the 8 balls into 3 groups of 2 and 1 group of 4. Weigh the group of 4 against one group of 2. If the scale tips, the lighter ball is in the group of 2. If the scale doesn't tip, the lighter ball is in the group of 4.

2nd weigh: Take the group of 4 balls, and divide it into 2 groups of 2. Weigh one group of 2 against the other. If the scale tips, the lighter ball is in the group that weighed less. If the scale doesn't tip, the lighter ball is one of the two remaining balls that were not weighed.

3rd weigh: Weigh the remaining two balls against each other. The lighter one will be the ball that weighs less.

By using this method, you will be able to determine the lighter ball with only three weighings.