# Program to count leaf nodes in a binary tree

A node is a leaf node if both left and right child nodes of it are NULL.

Here is an algorithm to get the leaf node count.

```getLeafCount(node)
1) If node is NULL then return 0.
2) Else If left and right child nodes are NULL return 1.
3) Else recursively calculate leaf count of the tree using below formula.
Leaf count of a tree = Leaf count of left subtree +
Leaf count of right subtree
``` Example Tree

Leaf count for the above tree is 3.

Implementation:

## C++

 `// C++ implementation to find leaf ` `// count of a given Binary tree  ` `#include ` `using` `namespace` `std; ` ` `  `/* A binary tree node has data,  ` `pointer to left child and  ` `a pointer to right child */` `struct` `node  ` `{  ` `    ``int` `data;  ` `    ``struct` `node* left;  ` `    ``struct` `node* right;  ` `};  ` ` `  `/* Function to get the count  ` `of leaf nodes in a binary tree*/` `unsigned ``int` `getLeafCount(``struct` `node* node)  ` `{  ` `    ``if``(node == NULL)      ` `        ``return` `0;  ` `    ``if``(node->left == NULL && node->right == NULL)  ` `        ``return` `1;         ` `    ``else` `        ``return` `getLeafCount(node->left)+  ` `            ``getLeafCount(node->right);  ` `}  ` ` `  `/* Helper function that allocates a new node with the  ` `given data and NULL left and right pointers. */` `struct` `node* newNode(``int` `data)  ` `{  ` `    ``struct` `node* node = (``struct` `node*)  ` `                    ``malloc``(``sizeof``(``struct` `node));  ` `    ``node->data = data;  ` `    ``node->left = NULL;  ` `    ``node->right = NULL;  ` `     `  `return``(node);  ` `}  ` ` `  `/*Driver code*/` `int` `main()  ` `{  ` `    ``/*create a tree*/` `    ``struct` `node *root = newNode(1);  ` `    ``root->left = newNode(2);  ` `    ``root->right = newNode(3);  ` `    ``root->left->left = newNode(4);  ` `    ``root->left->right = newNode(5);  ` `     `  `/*get leaf count of the above created tree*/` `cout << ``"Leaf count of the tree is : "``<<  ` `                ``getLeafCount(root) << endl;  ` `return` `0;  ` `}  ` ` `  `// This code is contributed by SHUBHAMSINGH10 `

## C

 `// C implementation to find leaf count of a given Binary tree ` `#include ` `#include ` ` `  `/* A binary tree node has data, pointer to left child  ` `   ``and a pointer to right child */` `struct` `node  ` `{ ` `    ``int` `data; ` `    ``struct` `node* left; ` `    ``struct` `node* right; ` `}; ` ` `  `/* Function to get the count of leaf nodes in a binary tree*/` `unsigned ``int` `getLeafCount(``struct` `node* node) ` `{ ` `  ``if``(node == NULL)        ` `    ``return` `0; ` `  ``if``(node->left == NULL && node->right==NULL)       ` `    ``return` `1;             ` `  ``else`  `    ``return` `getLeafCount(node->left)+ ` `           ``getLeafCount(node->right);       ` `} ` ` `  `/* Helper function that allocates a new node with the ` `   ``given data and NULL left and right pointers. */` `struct` `node* newNode(``int` `data)  ` `{ ` `  ``struct` `node* node = (``struct` `node*) ` `                       ``malloc``(``sizeof``(``struct` `node)); ` `  ``node->data = data; ` `  ``node->left = NULL; ` `  ``node->right = NULL; ` `   `  `  ``return``(node); ` `} ` ` `  `/*Driver program to test above functions*/`   `int` `main() ` `{ ` `  ``/*create a tree*/`   `  ``struct` `node *root = newNode(1); ` `  ``root->left        = newNode(2); ` `  ``root->right       = newNode(3); ` `  ``root->left->left  = newNode(4); ` `  ``root->left->right = newNode(5);     ` `   `  `  ``/*get leaf count of the above created tree*/` `  ``printf``(``"Leaf count of the tree is %d"``, getLeafCount(root)); ` `   `  `  ``getchar``(); ` `  ``return` `0; ` `} `

## Java

 `// Java implementation to find leaf count of a given Binary tree ` `  `  `/* Class containing left and right child of current  ` ` ``node and key value*/` `class` `Node  ` `{ ` `    ``int` `data; ` `    ``Node left, right; ` `  `  `    ``public` `Node(``int` `item)  ` `    ``{ ` `        ``data = item; ` `        ``left = right = ``null``; ` `    ``} ` `} ` `  `  `public` `class` `BinaryTree  ` `{ ` `    ``//Root of the Binary Tree ` `    ``Node root; ` `      `  `    ``/* Function to get the count of leaf nodes in a binary tree*/` `    ``int` `getLeafCount()  ` `    ``{ ` `        ``return` `getLeafCount(root); ` `    ``} ` `  `  `    ``int` `getLeafCount(Node node)  ` `    ``{ ` `        ``if` `(node == ``null``) ` `            ``return` `0``; ` `        ``if` `(node.left == ``null` `&& node.right == ``null``) ` `            ``return` `1``; ` `        ``else` `            ``return` `getLeafCount(node.left) + getLeafCount(node.right); ` `    ``} ` `  `  `    ``/* Driver program to test above functions */` `    ``public` `static` `void` `main(String args[])  ` `    ``{ ` `        ``/* create a tree */` `        ``BinaryTree tree = ``new` `BinaryTree(); ` `        ``tree.root = ``new` `Node(``1``); ` `        ``tree.root.left = ``new` `Node(``2``); ` `        ``tree.root.right = ``new` `Node(``3``); ` `        ``tree.root.left.left = ``new` `Node(``4``); ` `        ``tree.root.left.right = ``new` `Node(``5``); ` `          `  `        ``/* get leaf count of the abve tree */` `        ``System.out.println(``"The leaf count of binary tree is : "`  `                             ``+ tree.getLeafCount()); ` `    ``} ` `} ` ` `  `// This code has been contributed by Mayank Jaiswal(mayank_24) `

## Python

 `# Python program to count leaf nodes in Binary Tree ` ` `  `# A Binary tree node ` `class` `Node: ` `     `  `    ``# Constructor to create a new node ` `    ``def` `__init__(``self``, data): ` `        ``self``.data ``=` `data  ` `        ``self``.left ``=` `None` `        ``self``.right ``=` `None` ` `  `# Function to get the count of leaf nodes in binary tree ` `def` `getLeafCount(node): ` `    ``if` `node ``is` `None``: ` `        ``return` `0`  `    ``if``(node.left ``is` `None` `and` `node.right ``is` `None``): ` `        ``return` `1`  `    ``else``: ` `        ``return` `getLeafCount(node.left) ``+` `getLeafCount(node.right) ` ` `  ` `  `# Driver program to test above function ` `root ``=` `Node(``1``) ` `root.left ``=` `Node(``2``) ` `root.right ``=` `Node(``3``) ` `root.left.left ``=` `Node(``4``) ` `root.left.right ``=` `Node(``5``) ` ` `  `print` `"Leaf count of the tree is %d"` `%``(getLeafCount(root)) ` ` `  `#This code is contributed by Nikhil Kumar Singh(nickzuck_007) `

## C#

 `using` `System; ` ` `  `// C# implementation to find leaf count of a given Binary tree  ` ` `  `/* Class containing left and right child of current   ` ` ``node and key value*/` `public` `class` `Node ` `{ ` `    ``public` `int` `data; ` `    ``public` `Node left, right; ` ` `  `    ``public` `Node(``int` `item) ` `    ``{ ` `        ``data = item; ` `        ``left = right = ``null``; ` `    ``} ` `} ` ` `  `public` `class` `BinaryTree ` `{ ` `    ``//Root of the Binary Tree  ` `    ``public` `Node root; ` ` `  `    ``/* Function to get the count of leaf nodes in a binary tree*/` `    ``public` `virtual` `int` `LeafCount ` `    ``{ ` `        ``get` `        ``{ ` `            ``return` `getLeafCount(root); ` `        ``} ` `    ``} ` ` `  `    ``public` `virtual` `int` `getLeafCount(Node node) ` `    ``{ ` `        ``if` `(node == ``null``) ` `        ``{ ` `            ``return` `0; ` `        ``} ` `        ``if` `(node.left == ``null` `&& node.right == ``null``) ` `        ``{ ` `            ``return` `1; ` `        ``} ` `        ``else` `        ``{ ` `            ``return` `getLeafCount(node.left) + getLeafCount(node.right); ` `        ``} ` `    ``} ` ` `  `    ``/* Driver program to test above functions */` `    ``public` `static` `void` `Main(``string``[] args) ` `    ``{ ` `        ``/* create a tree */` `        ``BinaryTree tree = ``new` `BinaryTree(); ` `        ``tree.root = ``new` `Node(1); ` `        ``tree.root.left = ``new` `Node(2); ` `        ``tree.root.right = ``new` `Node(3); ` `        ``tree.root.left.left = ``new` `Node(4); ` `        ``tree.root.left.right = ``new` `Node(5); ` ` `  `        ``/* get leaf count of the abve tree */` `        ``Console.WriteLine(``"The leaf count of binary tree is : "` `+ tree.LeafCount); ` `    ``} ` `} ` ` `  `  ``// This code is contributed by Shrikant13 `

Output:

`The leaf count of binary tree is : 3`

Time & Space Complexities: Since this program is similar to traversal of tree, time and space complexities will be same as Tree traversal (Please see our Tree Traversal post for details)

Please write comments if you find any bug in the above programs/algorithms or other ways to solve the same problem.

## tags:

Tree Ola Cabs Ola Cabs Tree