What's the difference between the data structure Tree and Graph?

Question

Academically speaking, what\'s the essential difference between the data structure Tree and Graph? And how about the tree based search and Graph based search?

Answer 1

Instead of explaining I prefer to show it in pictures.

A tree in real time

A graph in real life use

Yes a map can be visualised as a graph data structure.

Seeing them like this makes life easier. Trees are used at places where we know that each node has only one parent. But graphs can have multiple predecessors(term parent is generally not used for graphs).

In real world, you can represent almost anything using graphs. I used a map, for example. If you consider each city as a node, it can be reached from multiple points. The points which lead to this node are called predecessors and the points which this node will lead to are called successors.

electrical circuit diagram, the plan of a house, computer network or a river system are few more examples of graphs. Many real world examples can be considered as graphs.

Technical diagram could be like this

Tree :

Graph :

Make sure to refer to below links. Those will answer almost all your questions on trees and graphs.

References :

1. http://www.introprogramming.info/english-intro-csharp-book/read-online/chapter-17-trees-and-graphs/#_Toc362296541

2. http://www.community-of-knowledge.de/beitrag/data-trees-as-a-means-of-presenting-complex-data-analysis/

3. Wikipedia