C- method find average distance from root to leaves - c

Question

How find average distance from root to all leaves in a binary tree
Dis­tance means num­ber of edges between the nodes.
The method get the root.
I think add new fields in node.
My code in C:
// A Binary Tree Node
struct Node
{
int data;
Node *left, *right;
};
int findDistance(Node *root)
{
// Base case
if (root == NULL)
return -1;
// Initialize distance
int dist = -1;
if ((root->data != NULL) ||
(dist = findDistance(root->left)) >= 0 + (dist = findDistance(root->right)) >= 0) /2
return dist + 1;
return dist;
}

Answer 1

I expect the following would work, but I have not tested it.
typedef struct
{
int Number; // Number of nodes in tree.
int TotalDepths; // Total of depth of each node.
} NAndTotal;
static NAndTotal FindNumberAndTotalDepth(Node *Root)
{
if (Root == NULL)
return (NAndTotal) { 0, 0 }; // No nodes in empty tree.
// Start an NAndTotal with information about the root node.
NAndTotal A = { 1, 0 }; // Root is 1 node at depth 0.
// Add the left subtree.
NAndTotal B = FindNumberAndTotalDepth(Root->left);
A.Number += B.Number; // Including left subtree adds its nodes.
A.TotalDepth += B.TotalDepth + B.Number; Each of its nodes become one deeper when placed under this node.
// Add the right subtree.
B = FindNumberAndTotalDepth(Root->right);
A.Number += B.Number; // Including right subtree adds its nodes.
A.TotalDepth += B.TotalDepth + B.Number; Each of its nodes become one deeper when placed under this node.
return A;
}
double FindAverage(Node *Root)
{
NAndTotal NT = FindNumberAndTotalDepth(Root);
return (double) NT.TotalDepths / NT.Number;
}