C Program to Count Leaf Nodes in a Binary Tree

#include <stdio.h>
#include <stdlib.h>

//Binary tree has data,pointer left&right child
struct binaryTreeNode{
int data;
struct binaryTreeNode *left;
struct binaryTreeNode *right;
};

//I created a new node
struct binaryTreeNode *createNodes(int data){
struct binaryTreeNode *node = (struct binaryTreeNode*)malloc(sizeof(struct binaryTreeNode));
// Assign data to newNode, leftchildren= NULL and rightchildren=NULL
node -> data = data;
node -> left = NULL;
node -> right = NULL;

return node;
}

struct binaryTreeNode *generateBinaryTree(){
//I define nodes
struct binaryTreeNode *node = createNodes(5);
node->left = createNodes(7);
node->right = createNodes(9);
node->left->left = createNodes(11);
node->left->right = createNodes(13);
node->right->left = createNodes(15);
node->right->right = createNodes(17);
node->left->left->left = createNodes(19);
node->right->left->left = createNodes(21);
node->right->left->right = createNodes(23);
node->right->left->left->left = createNodes(25);

return node;

}

// I define the function for count of leaf nodes
int count = 0;

int countLeafNodes(struct binaryTreeNode *node){

//I checked whether they are NULL by looking at left or right from the nodes.
if(node != NULL) {
countLeafNodes(node -> left);
//If it is NULL;
//the leaf which is null is printed and the initially 0 count is increased by 1.
if((node -> left == NULL) && (node -> right == NULL)) {

printf(“\n Leaf Node = %d \n”,node->data);
count++;

}

countLeafNodes(node -> right);


}

//If the node is not NULL then count = 0.

else {
return count;
}

}

int main() {

//I set root the binary tree nodes that I specified above
struct binaryTreeNode *node = generateBinaryTree();

printf(“ \n The count of leaf nodes in binary tree: %d” ,countLeafNodes(node));

return 0;
}

Output