#### Overview of this book

Data structures allow organizing data efficiently. They are critical to various problems and their suitable implementation can provide a complete solution that acts like reusable code. In this book, you will learn how to use various data structures while developing in the C# language as well as how to implement some of the most common algorithms used with such data structures. At the beginning, you will get to know arrays, lists, dictionaries, and sets together with real-world examples of your application. Then, you will learn how to create and use stacks and queues. In the following part of the book, the more complex data structures will be introduced, namely trees and graphs, together with some algorithms for searching the shortest path in a graph. We will also discuss how to organize the code in a manageable, consistent, and extendable way. By the end of the book,you will learn how to build components that are easy to understand, debug, and use in different applications.
Title Page
Packt Upsell
Contributors
Preface
Free Chapter
Getting Started
Arrays and Lists
Stacks and Queues
Dictionaries and Sets
Variants of Trees
Exploring Graphs
Summary
Other Books You May Enjoy
Index

## Concept of graphs

Let's start with the question what is a graph? Broadly speaking, a graph is a data structure that consists of nodes (also called vertices) and edges. Each edge connects two nodes. A graph data structure does not require any specific rules regarding connections between nodes, as shown in the following diagram:

The afore mentioned concept seems very simple, doesn't it? Let's try to analyze the preceding graph to eliminate any doubts. It contains nine nodes with numbers between 1 and 9 as values. Such nodes are connected by 11 edges, such as between nodes 2 and 4. Moreover, a graph can contain cycles, for example, with nodes indicated by 2, 3, and 4, as well as separate groups of nodes, which are not connected together. However, what about the topic of parent and child nodes, which you know from learning about trees? As there are no specific rules about connections in a graph, such concepts are not used in this case.

### Note

A graph can also contain self-loops. Each is an edge that...