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

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