Data Structure Graphs Survival Guide

Introduction

We have all heard about graphs within the computer science field, and probably just thought about a normal graph only to find out that was completely wrong. Well don’t worry, I am here to help with a quick survival guide.

Nodes

• Nodes are also known as vertices or vertex
• Can also have value

Example of a graph

In the example above the nodes are shown as circles with different number values.

Arrows

• Also known as edges.
• Connects the nodes with a direction

Connected/Unconnected

• A graph is connected if all of the nodes are linked in one way or another. Let’s take a look at an example.

Example of an unconnected graph

In the example above, you can see that Nodes 8 and 9 aren't connected to the rest of the graph.

Cyclic

• Cyclic graph is when you can have an infinite loop between nodes.
• Another way to think about it would be if you follow the direction of the graph and find your way back to a node you’ve already traversed.

Example of a cyclic graph

In the example above, you can see that we have a cyclic graph. The reason is that between nodes 3,4, and 5 you can see that you can go in the same direction an infinite amount of times.

Acyclic

• A graph that has no cycles.

Directed

• A directed graph is when the arrows or edges are pointed to other nodes

Example of a directed graph

Undirected

• An undirected graph is when the edges aren’t pointing to another node.

Example of an undirected graph