CSE 5010
DATA STRUCTURES AND ALGORITHMS
INTRODUCTION
Anjana Wijesinghe ​
MSc in IT (Reading) (SLIIT) , BSc (Hons) (WUSL)
OBJECTIVES
• Be familiar with problem-solving.
• Be able to develop (and implement) algorithms.
• Be able to trace algorithms.
• Be able to select appropriate data structures and algorithms for given problems.
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PREREQUISITES
• Variables and expressions.
• Methods (functions or procedures ).
• Decision structures( like if-statements and switch-statements.
• Iteration structures (for-loops and while-loops).
• Classes and objects
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OUTLINE
Introduction
Data Structures
Algorithms
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INTRODUCTION 01
WHAT IS DATA?
Data
 A collection of facts from which a conclusion may be drawn.
 e.g. Data: Temperature 35°C; Conclusion: It is hot.
Types of data
 Textual: For example, your name (Aruna)
 Numeric: For example, your ID (090254)
 Audio: For example, your voice
 Video: For example, your voice and picture
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DATA TYPES & DATA STRUCTURES
Applications/programs read data, store data temporarily, process it and finally
output results.
What is data? Numbers, Characters, etc.
Data
Application/ Data
Program
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DATA TYPES & DATA STRUCTURES CONT.
Data is classified into data types. e.g. char, float, int, etc.
A data type is
(i) a domain of allowed values and
(ii) a set of operations on these values.
Compiler signals an error if the wrong operation is performed on data of a certain
type. For example, char x,y,z; z = x*y is not allowed.
Data Type
Domain
Operations
boolean
0,1
and, or, =, etc.
char
ASCII
=, <>, <, etc.
integer
-maxint to
+maxint
+, _, =, ==,
<>, <, etc.
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DATA
STRUCTURES
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WHAT ARE DATA STRUCTURES?
Data structures are ways to store and organize data to facilitate access and
modifications.
•Purpose: To manage and organize data efficiently.
•Types: Linear (e.g., arrays, linked lists) and Non-linear (e.g., trees, graphs).
•Importance: They form the foundation for designing efficient algorithms.
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TYPES OF DATA STRUCTURES
Array
Linked List
Tree
Queue
Stack
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DATA STRUCTURE OPERATIONS
Navigating
• Accessing each data element exactly once so that certain items in the data may
be processed
Searching
• Finding the location of the data element (key) in the structure
Insertion
• Adding a new data element to the structure
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DATA STRUCTURE OPERATIONS CONT.
Deletion
•
Removing a data element from the structure
Sorting
•
Arrange the data elements in a logical order (ascending/descending)
Merging
•
Combining data elements from two or more data structures into one
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COMMON DATA STRUCTURES
Linear Data Structures:
• Array: Fixed-size sequence of elements of the same type.
• Linked List: Sequence of elements, where each element points to the next.
• Stack: LIFO (Last In, First Out) structure.
• Queue: FIFO (First In, First Out) structure.
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COMMON DATA STRUCTURES CONT.
Non-linear Data Structures:
• Tree: Hierarchical structure with nodes.
• Graph: Set of nodes connected by edges.
• Heap: A special tree-based structure.
• Hash Table: Stores key-value pairs for efficient lookup.
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ALGORITHMS
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WHAT IS ALGORITHM?
A step-by-step procedure or formula for solving a problem.
•Purpose: To perform operations on data structures.
•Characteristics: Correctness, efficiency, and clarity.
•Importance: Efficient algorithms save time and resources.
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COMMON ALGORITHM TYPES
Sorting Algorithms:
•Bubble Sort: Simple comparison-based sort.
•Quick Sort: Divide-and-conquer algorithm.
•Merge Sort: Divide-and-conquer algorithm that merges sorted arrays.
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COMMON ALGORITHM TYPES CONT.
Searching Algorithms:
•Linear Search: Sequential search through elements.
•Binary Search: Efficient search in sorted arrays.
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COMMON ALGORITHM TYPES CONT.
Graph Algorithms:
•Dijkstra’s Algorithm: Shortest path in weighted graphs.
•Depth-First Search (DFS): Traversal of nodes in a depthward motion.
•Breadth-First Search (BFS): Traversal of nodes level by level.
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SUMMARY
Data Structures and Algorithms are fundamental concepts in computer science for
efficiently organizing, managing, and processing data.
Data structures, including linear (arrays, linked lists) and non-linear (trees, graphs),
are key for efficient data storage and retrieval.
Algorithms, such as sorting, searching, and graph algorithms, are step-by-step
procedures for problem-solving.
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THANK
YOU!