BST with child count

You are given a special binary search tree where each node contains the
number of nodes in its child-trees in addition to the key.

Example:

                (50,4)
             /           \
          (30,4)        (70,2)
         /      \       /     \
      (20,2)  (40,0) (60,0)  (80,0)
      /    \
    (10,0) (25,0)


Given, 10, 40, the required value is 3, since we have 20, 25, 30

Answer:

int FindCount(TreeNode* n, int min_val, int max_val)
{
    if (n)
    {
        if ( n->val is between min_val and max_val )
            return n->child_count - 2;
        else if ( n->val < min_val )
            return FindCount(n->right, min_val, max_val);
        else
            return FindCount(n->left, min_val, max_val);
    }
    return 0;
}