Tree Terminology: Path
- Define tree-related terminologies.
Suppose is a sequence of nodes in a tree such that is the parent of , which is the parent of , and so on, down to , which is the parent of . Then is called a path from to .

For example, the sequence is a path from root, , to leaf, .
The length of a path is , where is the number of nodes on it.
A path may consist of a single node (), in which case the length of the path is .