Given a Binary tree, count total number of non-leaf nodes in the tree

Examples:

Input : Output :2ExplanationIn the above tree only two nodes 1 and 2 are non-leaf nodes

We recursively traverse the given tree. While traversing, we count non-leaf nodes in left and right subtrees and add 1 to the result.

// CPP program to count total number of // non-leaf nodes in a binary tree #include <bits/stdc++.h> 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; }; /* 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 = new Node; node->data = data; node->left = node->right = NULL; return (node); } /* Computes the number of non-leaf nodes in a tree. */ int countNonleaf(struct Node* root) { // Base cases. if (root == NULL || (root->left == NULL && root->right == NULL)) return 0; // If root is Not NULL and its one of its // child is also not NULL return 1 + countNonleaf(root->left) + countNonleaf(root->right); } /* Driver program to test size function*/ int main() { struct Node* root = newNode(1); root->left = newNode(2); root->right = newNode(3); root->left->left = newNode(4); root->left->right = newNode(5); cout << countNonleaf(root); return 0; }

Output:

2

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

**Practice Tags :**