出典:Wiktionary
出典:Wikipedia
出典:『Wikipedia』 (2011/07/04 19:55 UTC 版)
In computer science, a leaf node or external node is a node of a tree data structure that has zero child nodes. Often, leaf nodes are the nodes farthest from the root node. In the graph theory tree, a leaf node is a vertex of degree 1 other than the root (except when the tree has only one vertex; then the root, too, is a leaf). Every tree has at least one leaf.