40 Algorithms Every Programmer Should Know

Terminology

Let's look into some of the terminology related to the tree data structure:

Root node	A node with no parent is called the root node. For example, in the following diagram, the root node is A. In algorithms, usually, the root node holds the most important value in the tree structure.
Level of a node	The distance from the root node is the level of a node. For example, in the following diagram, the level of nodes D, E, and F is two.
Siblings nodes	Two nodes in a tree are called siblings if they are at the same level. For example, if we check the following diagram, nodes B and C are siblings.
Child and parent node	A node, F, is a child of node C, if both are directly connected and the level of node C is less than node F