Transcript Data Structures Basics

Chapter 1
Basic Concepts
Objectives
•
•
•
•
•
Use pseudocode in the development of algorithms
Understand the need for Abstract Data Type (ADT)
Understand the implementation of ADTs
Use void pointers and pointer to functions
Understand the role of Big-O notation
Data Structures: A Pseudocode Approach with C, Second Edition
1
Pseudocode
Pseudocode is an English-like representation of the algorithm logic. It
consists of an extended version of the basic algorithmic constructs:
sequence, selection, and iteration.
• Algorithm Header
• Purpose, Condition, and Return
• Statement Numbers
• Variables
• Statment Constructs
• Algorithm Analysis
Data Structures: A Pseudocode Approach with C, Second Edition
2
Data Structures: A Pseudocode Approach with C, Second Edition
3
Data Structures: A Pseudocode Approach with C, Second Edition
4
The Abstract Data Type
An ADT consists of a data declaration packaged
together with the operations that are meaningful
on the data while embodying the structured
principles of encapsulation and data hiding. In this section
we define the basic parts of an ADT.
• Atomic and Composite Data
• Data Type
• Data Structure
• Abstract Data Type
Data Structures: A Pseudocode Approach with C, Second Edition
5
Data Structures: A Pseudocode Approach with C, Second Edition
6
Data Structure
Aggregation of atomic and composite data into a set with defined
relationships. Structure refers to a set of rules that hold the data
together.
•
A combination of elements in which each is either a data type or another
data structure.
•
A set of associations of relationship involving combined elements.
Example:
Data Structures: A Pseudocode Approach with C, Second Edition
7
Data Structures: A Pseudocode Approach with C, Second Edition
8
Abstract Data Type




ADT users are NOT concerned with how the task is done but rather what it
can do.
An abstract data type is a data declaration packaged together with the
operations that are meaningful for the data type.
We encapsulate the data and the operations on the data, and then hide
them from the user.
All references to and manipulation of the data in a data structure are
handled through defined interfaces to the structure.
Data Structures: A Pseudocode Approach with C, Second Edition
9
Model for an Abstract Data Type
In this section we provide a conceptual
model for an Abstract Data Type (ADT).
• ADT Operation – passage like
• ADT Data Structure – controlled
entirely
Data Structures: A Pseudocode Approach with C, Second Edition
10
Data Structures: A Pseudocode Approach with C, Second Edition
11
ADT Implementations
There are two basic structures we can use to
implement an ADT list: arrays and linked lists.
In this section we discuss the basic
linked-list implementation.
• Array Implementation
• Linked List Implemenation
Data Structures: A Pseudocode Approach with C, Second Edition
12
Data Structures: A Pseudocode Approach with C, Second Edition
13
Data Structures: A Pseudocode Approach with C, Second Edition
14
Data Structures: A Pseudocode Approach with C, Second Edition
15
Generic Code for ADT
In this section we discuss and provide examples
of two C tools that are required to implement
an ADT.
• Pointer to Void
• Pointer to Function
Data Structures: A Pseudocode Approach with C, Second Edition
16
Data Structures: A Pseudocode Approach with C, Second Edition
17
Data Structures: A Pseudocode Approach with C, Second Edition
18
Data Structures: A Pseudocode Approach with C, Second Edition
19
Data Structures: A Pseudocode Approach with C, Second Edition
20
(Continued)
Data Structures: A Pseudocode Approach with C, Second Edition
21
Data Structures: A Pseudocode Approach with C, Second Edition
22
Data Structures: A Pseudocode Approach with C, Second Edition
23
Data Structures: A Pseudocode Approach with C, Second Edition
24
Data Structures: A Pseudocode Approach with C, Second Edition
25
(Continued)
Data Structures: A Pseudocode Approach with C, Second Edition
26
Data Structures: A Pseudocode Approach with C, Second Edition
27
Data Structures: A Pseudocode Approach with C, Second Edition
28
Data Structures: A Pseudocode Approach with C, Second Edition
29
Data Structures: A Pseudocode Approach with C, Second Edition
30
Data Structures: A Pseudocode Approach with C, Second Edition
31
Data Structures: A Pseudocode Approach with C, Second Edition
32
Data Structures: A Pseudocode Approach with C, Second Edition
33
Data Structures: A Pseudocode Approach with C, Second Edition
34
Algorithm Efficiency
To design and implement algorithms, programmers
must have a basic understanding of what constitutes
good, efficient algorithms.
Linear Loops
-Efficiency is a function of the number of intstructions.
- Loop update either adds or subtracts.
• Logarithmic Loops
-The controlling variable is either multiplied or divided in each iteration.
- The number of iteration is a function of the multiplier or divisor.
• Nested Loops
- The number of iterations is the total number which is the product of the number of
iterations in the inner loop and number of iterations in the outer loop.
• Big-O Notation
-Not concerned with exact measurement of efficiency but with the magnitude.
- A dominant factor determines the magnitute.
Data Structures: A Pseudocode Approach with C, Second Edition
35