# 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.

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:

`// CPP program to print the number of set bits ` `// in each node of the binary tree ` ` ` `#include <bits/stdc++.h> ` ` ` `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; ` `} ` |

*chevron_right*

*filter_none*

**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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