程序中的数据采用“树形结构”作为其数据结构。具体的，采用的是“二叉排序树”。 二叉排序树或者是一棵空树，或者是具有下列性质的二叉树：（1）若它的左子树不空，则左子树上所有结点的值均小于它的根结点的值；（2）若它的右子树不空，则右子树上所有结点的值均大于它的根结点的值；（3）它的左右子树也分别为二叉排序树。-Process the data in a　tree structure　as its data structure. Concrete, used the　binary sort tree.　Binary sort tree or an empty tree, or the nature of the binary tree with the following: (1) if it s left subtree is not empty, then the left sub-tree of all nodes is less than the value of its root point value　(2) if it s right subtree is not empty, then the right sub-tree value of all the nodes were larger than the value of its root node　(3) around its subtree are also binary sort tree.