# Print the number of set bits in each node of a Binary Tree

Given a Binary Tree. The task is to print the number of set bits in each of the nodes in the Binary Tree. ## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

The idea is to traverse the given binary tree using any tree traversal method, and for each node calculate the number of set bits and print it.

Note: One can also use the __builtin_popcount() function available in C++ to directly count the number of set bits in an integer.

Below is the implementation of the above approach:

## C++

 `// CPP program to print the number of set bits ` `// in each node of the binary tree ` ` `  `#include ` ` `  `using` `namespace` `std; ` ` `  `// Binary Tree node ` `struct` `Node { ` `    ``int` `data; ` `    ``struct` `Node *left, *right; ` `}; ` ` `  `// Utility function that allocates a new Node ` `Node* newNode(``int` `data) ` `{ ` `    ``Node* node = ``new` `Node; ` `    ``node->data = data; ` `    ``node->left = node->right = NULL; ` `    ``return` `(node); ` `} ` ` `  `// Function to print the number of set bits ` `// in each node of the binary tree ` `void` `printSetBit(Node* root) ` `{ ` `    ``if` `(root == NULL) ` `        ``return``; ` ` `  `    ``// Print the number of set bits of ` `    ``// current node using __builtin_popcount() ` `    ``cout << ``"Set bits in Node "` `<< root->data << ``" = "` `<< ` `                  ``__builtin_popcount(root->data) << ``"\n"``; ` ` `  `    ``// Traverse Left Subtree ` `    ``printSetBit(root->left); ` ` `  `    ``// Traverse Right Subtree ` `    ``printSetBit(root->right); ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``Node* root = newNode(16); ` `    ``root->left = newNode(13); ` `    ``root->left->left = newNode(14); ` `    ``root->left->right = newNode(12); ` `    ``root->right = newNode(11); ` `    ``root->right->left = newNode(10); ` `    ``root->right->right = newNode(16); ` ` `  `    ``printSetBit(root); ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java program to print the number of set bits ` `// in each node of the binary tree ` `import` `java.util.*; ` ` `  `class` `GFG  ` `{ ` ` `  `// Binary Tree node ` `static` `class` `Node  ` `{ ` `    ``int` `data; ` `    ``Node left, right; ` `}; ` ` `  `// Utility function that allocates a new Node ` `static` `Node newNode(``int` `data) ` `{ ` `    ``Node node = ``new` `Node(); ` `    ``node.data = data; ` `    ``node.left = node.right = ``null``; ` `    ``return` `(node); ` `} ` ` `  `// Function to print the number of set bits ` `// in each node of the binary tree ` `static` `void` `printSetBit(Node root) ` `{ ` `    ``if` `(root == ``null``) ` `        ``return``; ` ` `  `    ``// Print the number of set bits of ` `    ``// current node using __builtin_popcount() ` `    ``System.out.print(``"Set bits in Node "` `+ root.data + ``" = "` `+ ` `                      ``Integer.bitCount(root.data) + ``"\n"``); ` ` `  `    ``// Traverse Left Subtree ` `    ``printSetBit(root.left); ` ` `  `    ``// Traverse Right Subtree ` `    ``printSetBit(root.right); ` `} ` ` `  `// Driver code ` `public` `static` `void` `main(String[] args)  ` `{ ` `    ``Node root = newNode(``16``); ` `    ``root.left = newNode(``13``); ` `    ``root.left.left = newNode(``14``); ` `    ``root.left.right = newNode(``12``); ` `    ``root.right = newNode(``11``); ` `    ``root.right.left = newNode(``10``); ` `    ``root.right.right = newNode(``16``); ` ` `  `    ``printSetBit(root); ` `} ` `} ` ` `  `// This code is contributed by PrinciRaj1992  `

## Python3

 `# Python3 program to print the number of set bits ` `# in each node of the binary tree ` ` `  `# Binary Tree node ` `class` `Node: ` `    ``def` `__init__(``self``): ` `        ``self``.data ``=` `None` `        ``self``.left ``=` `None` `        ``self``.right ``=` `None` ` `  `# Utility function that allocates a new Node ` `def` `newNode(data): ` `    ``node ``=` `Node() ` `    ``node.data ``=` `data ` `    ``node.left ``=` `None` `    ``node.right ``=` `None` `    ``return` `node ` ` `  `# Function to print the number of set bits ` `# in each node of the binary tree ` `def` `printSetBit(root: Node): ` `    ``if` `root ``is` `None``: ` `        ``return` ` `  `    ``# Print the number of set bits of ` `    ``# current node using count() ` `    ``print``(``"Set bits in Node %d = %d"` `%`  `         ``(root.data, ``bin``(root.data).count(``'1'``))) ` ` `  `    ``# Traverse Left Subtree ` `    ``printSetBit(root.left) ` ` `  `    ``# Traverse Right Subtree ` `    ``printSetBit(root.right) ` ` `  `# Driver Code ` `if` `__name__ ``=``=` `"__main__"``: ` `    ``root ``=` `newNode(``16``) ` `    ``root.left ``=` `newNode(``13``) ` `    ``root.left.left ``=` `newNode(``14``) ` `    ``root.left.right ``=` `newNode(``12``) ` `    ``root.right ``=` `newNode(``11``) ` `    ``root.right.left ``=` `newNode(``10``) ` `    ``root.right.right ``=` `newNode(``16``) ` ` `  `    ``printSetBit(root) ` ` `  `# This code is contributed by ` `# sanjeev2552 `

## C#

 `// C# program to print the number of set bits ` `// in each node of the binary tree ` `using` `System; ` `     `  `class` `GFG  ` `{ ` ` `  `// Binary Tree node ` `public` `class` `Node  ` `{ ` `    ``public` `int` `data; ` `    ``public` `Node left, right; ` `}; ` ` `  `// Utility function that allocates a new Node ` `static` `Node newNode(``int` `data) ` `{ ` `    ``Node node = ``new` `Node(); ` `    ``node.data = data; ` `    ``node.left = node.right = ``null``; ` `    ``return` `(node); ` `} ` ` `  `// Function to print the number of set bits ` `// in each node of the binary tree ` `static` `void` `printSetBit(Node root) ` `{ ` `    ``if` `(root == ``null``) ` `        ``return``; ` ` `  `    ``// Print the number of set bits of ` `    ``// current node using __builtin_popcount() ` `    ``Console.Write(``"Set bits in Node "` `+ root.data +  ` `                  ``" = "` `+ bitCount(root.data) + ``"\n"``); ` ` `  `    ``// Traverse Left Subtree ` `    ``printSetBit(root.left); ` ` `  `    ``// Traverse Right Subtree ` `    ``printSetBit(root.right); ` `} ` ` `  `static` `int` `bitCount(``int` `x) ` `{ ` `    ``int` `setBits = 0; ` `    ``while` `(x != 0) ` `    ``{ ` `        ``x = x & (x - 1); ` `        ``setBits++; ` `    ``} ` `    ``return` `setBits; ` `}  ` ` `  `// Driver code ` `public` `static` `void` `Main(String[] args)  ` `{ ` `    ``Node root = newNode(16); ` `    ``root.left = newNode(13); ` `    ``root.left.left = newNode(14); ` `    ``root.left.right = newNode(12); ` `    ``root.right = newNode(11); ` `    ``root.right.left = newNode(10); ` `    ``root.right.right = newNode(16); ` ` `  `    ``printSetBit(root); ` `} ` `} ` ` `  `// This code is contributed by 29AjayKumar `

Output:

```Set bits in Node 16 = 1
Set bits in Node 13 = 3
Set bits in Node 14 = 3
Set bits in Node 12 = 2
Set bits in Node 11 = 3
Set bits in Node 10 = 2
Set bits in Node 16 = 1
```

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