Binary Trees
•If a node is a root, the level is 1. If a node is not the root,
–then it has a level 1 greater than its parent.
•If the tree is entirely empty,
–then it has a height of zero.
•Otherwise, its height is equal to the maximum level of its nodes.
•Using this definition,
–the trees shown previously have the height of 3, 5, and 5.