6. Trees

When we see a tree in our everyday lives the roots are generally in the ground and the leaves are up in the air. The branches of a tree spread out from the roots in a more or less organized fashion. The word tree is used in Computer Science when talking about a way data may be organized. Trees have some similarilties to the linked list organization found in Chap. 4. In a tree there are nodes which have links to other nodes. In a linked list each node has one link, to the next node in the list. In a tree each node may have two or more links to other nodes. A tree is not a sequential data structure. It is organized like a tree, except the root is at the top of tree data structures and the leaves are at the bottom. A tree in computer science is usually drawn inverted when compared to the trees we see in nature. There are many uses for trees in computer science. In this chapter we’ll explore trees and when it makes sense to build and or use a tree in a program. Not every program will need a tree data structure. Nevertheless, trees are used in many types of programs. A knowledge of them is not only a necessity, proper use of them can greatly simplify some types of programs.