Here is the recursive definition of a binary tree:
A binary tree is either the empty set or a triple T = (x,L,R), where x is a node and L and R are disjoint binary trees, neither of which contains.
The node x is called the root of the tree T, and the subtrees L and R are called the left subtree and the right subtree of T rooted at x.
Here is an equivalent, nonerecursive defination for binary trees:
A binay tree is an ordered tree in which every internal node has degree 2.
【DataStrcutre】Introduction and description of Binary Trees,布布扣,bubuko.com
【DataStrcutre】Introduction and description of Binary Trees
原文地址:http://blog.csdn.net/sxb0841901116/article/details/38647921