Each node in the tree represents a record in the table, and the value in the node is the position of the record in the table. Usually, the binary tree of this search process is called binary decision tree.

The node of binary decision tree is the subscript or position of each element in the table. For example, there is a file 1 1, 22, 33, 44, 55, 66, and I want to find out whether 44 is in this file. By using the idea of half search, this file can be constructed as a binary decision tree.

The root node is 3. Note that the nodes of the binary decision tree are subscripts or positions, and 33 cannot be written here.