# Preorder and Postorder Traversal of Rooted Trees

Preorder and Postorder Traversal of Rooted Trees

Many algorithms that make use of trees often traverse the tree in some order, that is, they visit each vertex in a systematic way. Two commonly used traversals are preorder and postorder. A preorder traversal of is defined by a two-step recursion:

T

1. visit the root and

2. visit in preorder the subtrees of the root of from left to right.

T

A postorder is similarly defined as:

1. visit in postorder the subtrees of from left to right and

T

2. visit the root.

This Demonstration shows the preorder and postorder traversals corresponding to a randomly labeled rooted tree with a chosen number of vertices.