How to implement BST Tree in c++?

Question

I mean I want to make a BST tree by few nodes which each of that has a frequency so I want to implement a BST tree has been built by current nodes ,

 the low frequency nodes must be left child of parent codes and vice versa and it start with the highest frequency . The calculation must be the lowest one created by nodes in tree.

 

For example:

Node 1 : 0.9

Node 2: 0.4                The calculation must be the lowest one created by nodes:  1 * 0.9 + 2 * 0.6 + 3 * 0.1=  2.4

Node 3: 0.1

 

                                                               Node 1

   

                                             Node 2

 

                              Node 3