Lesson 1 overview
- 1. Lesson 1 - Overview 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM BY: AREGATON
- 2. What is data structure and algorithm? A data structure is an arrangement of data in a computer’s memory (or sometimes on a disk). Data structures include arrays, linked lists, stacks, binary trees, and hash tables, among others. Algorithms manipulate the data in these structures in various ways, such as searching for a particular data item and sorting the data. What sorts of problems can you solve with a knowledge of these topics? As a rough approximation, we might divide the situations in which they’re useful into three categories: Real-world data storage Programmer’s tools Modeling 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 2
- 3. Real-World Data Storage Many of the structures and techniques we’ll discuss are concerned with how to handle real-world data storage. By real-world data, we mean data that describes physical entities external to the computer. As some examples, a personnel record describes an actual human being, an inventory record describes an existing car part or grocery item, and a financial transaction record describes, say, an actual check written to pay the electric bill. 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 3
- 4. Programmer’s Tools Not all data storage structures are used to store real-world data. Typically, real-world data is accessed more or less directly by a program’s user. Some data storage structures, however, are not meant to be accessed by the user, but by the program itself. A programmer uses such structures as tools to facilitate some other operation. Stacks, queues, and priority queues are often used in this way. We’ll see examples as we go along. 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 4
- 5. Real-World Modeling Some data structures directly model real-world situations. The most important data structure of this type is the graph. You can use graphs to represent airline routes between cities or connections in an electric circuit or tasks in a project. 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 5
- 6. CHARACTERISTICS OF DATA STRUCTURE 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 6
- 7. CHARACTERISTICS OF DATA STRUCTURE 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 7
- 8. Overview of Algorithms Many of the algorithms we’ll discuss apply directly to specific data structures. For most data structures, you need to know how to Insert a new data item. Search for a specified item. Delete a specified item. 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 8
- 9. Some Definitions Database We’ll use the term database to refer to all the data that will be dealt with in a particular situation. Record Records are the units into which a database is divided. They provide a format for storing information. Field A record is usually divided into several fields. A field holds a particular kind of data. 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 9
- 10. SAMPLE RECORD 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 10 RECORDS FIELDS
- 11. Key To search for a record within a database, you need to designate one of the record’s fields as a key (or search key). 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 11
- 12. SUMMARY • A data structure is the organization of data in a computer’s memory or in a disk file. • The correct choice of data structure allows major improvements in program efficiency. • Examples of data structures are arrays, stacks, and linked lists. • An algorithm is a procedure for carrying out a particular task. • In Java, an algorithm is usually implemented by a class method. • Many of the data structures and algorithms described in this book are most often used to build databases. 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 12
- 13. SUMMARY • Some data structures are used as programmer’s tools: They help execute an algorithm. • Other data structures model real-world situations, such as telephone lines running between cities. • A database is a unit of data storage composed of many similar records. • A record often represents a real-world object, such as an employee or a car part. • A record is divided into fields. Each field stores one characteristic of the object described by the record. • A key is a field in a record that’s used to carry out some operation on the data. For example, personnel records might be sorted by a LastName field. • A database can be searched for all records whose key field has a certain value. This value is called a search key. 4/4/2021 PC-108 DATA STRUCTURE AND ALGORITHM 13