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

• Difficulty Level : Medium
• Last Updated : 29 Jun, 2021

Given a Binary Tree. The task is to print the number of set bits in each of the nodes in the Binary Tree.

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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`

## Javascript

 ``
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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