Random traversal of binary search tree

//C Program 
//Random traversal in Binary search tree
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
//Structure of Binary Search Tree node
struct Node
{
	int data;
	struct Node *left, *right;
};
//Adding a new node in binary search tree
void add(struct Node **root, int data)
{
	//Create a dynamic node of binary search tree 
	struct Node *new_node = (struct Node *) malloc(sizeof(struct Node));
	if (new_node != NULL)
	{
		//Set data and pointer values
		new_node->data = data;
		//Initially node left-pointer is NULL
		new_node->left = NULL;
		//Initially node right-pointer is NULL
		new_node->right = NULL;
		if ( *root == NULL)
		{
			//When adds a first node in binary tree
			*root = new_node;
		}
		else
		{
			struct Node *find = *root;
			//iterate binary tree and add new node to proper position
			while (find != NULL)
			{
				if (find->data > data)
				{
					if (find->left == NULL)
					{
						find->left = new_node;
						break;
					}
					else
					{ //visit left sub-tree
						find = find->left;
					}
				}
				else
				{
					if (find->right == NULL)
					{
						find->right = new_node;
						break;
					}
					else
					{
						//visit right sub-tree
						find = find->right;
					}
				}
			}
		}
	}
	else
	{
		printf("Memory Overflow\n");
		exit(0); //Terminate program execution
	}
}
//Traverse the random nodes in given binary search tree
void random_traversal(struct Node *root)
{
	if (root != NULL)
	{
		//Check whether random number is Even or not
		if (rand() % 2 == 0)
		{
			//When visiting on left subtree first
			random_traversal(root->left);
			//display node value
			printf("%3d ", root->data);
			//When visiting on right subtree second
			random_traversal(root->right);
		}
		else
		{
			//When visiting on right subtree first
			random_traversal(root->right);
			//display node value
			printf("%3d ", root->data);
			//When visiting on left subtree second
			random_traversal(root->left);
		}
	}
}
int main()
{
	srand(time(NULL));
	struct Node *root = NULL;
	//Add nodes in binary search tree
	/*
	        6
	      /    \
	     /      \
	    3        9
	   /  \     / \
	  1    5   7   20
	      /       /
	     4       15

	*/
	add( & root, 6);
	add( & root, 3);
	add( & root, 9);
	add( & root, 1);
	add( & root, 5);
	add( & root, 7);
	add( & root, 4);
	add( & root, 15);
	random_traversal(root);
	printf("\n");
	random_traversal(root);
	printf("\n");
	random_traversal(root);
	printf("\n");
	random_traversal(root);
	return 0;
}

Output

  1   3   4   5   6  15   9   7
  5   4   3   1   6   7   9  15
  7   9  15   6   5   4   3   1
  1   3   5   4   6   7   9  15