Count Non-Leaf nodes in a Binary Tree

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

Examples:

Input :


Output :2
Explanation
In 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.

C++

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// 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;
}

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Java














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// Java program to count total number of  


// non-leaf nodes in a binary tree  


class GfG {  


  


/* A binary tree node has data, pointer to  


left child and a pointer to right child */


static class Node {  


    int data;  


    Node left;  


    Node right;  


} 


  


/* Helper function that allocates a new node with the  


given data and NULL left and right pointers. */


static Node newNode(int data)  


{  


    Node node = new Node();  


    node.data = data;  


    node.left = null; 


    node.right = null;  


    return (node);  


}  


  


/* Computes the number of non-leaf nodes in a tree. */


static int countNonleaf(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*/


public static void main(String[] args)  


{  


    Node root = newNode(1);  


    root.left = newNode(2);  


    root.right = newNode(3);  


    root.left.left = newNode(4);  


    root.left.right = newNode(5);  


    System.out.println(countNonleaf(root));  


} 


}  



















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Python3














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# Python3 program to count total number  


# of non-leaf nodes in a binary tree 


  


# class that allocates a new node with the  


#given data and None left and right pointers.  


class newNode: 


    def __init__(self,data): 


        self.data = data  


        self.left = self.right = None


  


# Computes the number of non-leaf  


# nodes in a tree.  


def countNonleaf(root): 


      


    # Base cases.  


    if (root == None or (root.left == None and 


                         root.right == None)):  


        return 0


  


    # If root is Not None and its one of   


    # its child is also not None  


    return (1 + countNonleaf(root.left) + 


                countNonleaf(root.right)) 


  


# Driver Code 


if __name__ == '__main__': 


  


    root = newNode(1)  


    root.left = newNode(2)  


    root.right = newNode(3)  


    root.left.left = newNode(4)  


    root.left.right = newNode(5)  


    print(countNonleaf(root)) 


  


# This code is contributed by PranchalK 



















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C#














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// C# program to count total number of  


// non-leaf nodes in a binary tree 


using System; 


  


class GfG  


{  


  


    /* A binary tree node has data, pointer to  


    left child and a pointer to right child */


    class Node {  


        public int data;  


        public Node left;  


        public Node right;  


    } 


  


    /* Helper function that allocates a new node with the  


    given data and NULL left and right pointers. */


    static Node newNode(int data)  


    {  


        Node node = new Node();  


        node.data = data;  


        node.left = null; 


        node.right = null;  


        return (node);  


    }  


  


    /* Computes the number of non-leaf nodes in a tree. */


    static int countNonleaf(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 code*/


    public static void Main(String[] args)  


    {  


        Node root = newNode(1);  


        root.left = newNode(2);  


        root.right = newNode(3);  


        root.left.left = newNode(4);  


        root.left.right = newNode(5);  


        Console.WriteLine(countNonleaf(root));  


    } 


} 


  


// This code is contributed by PrinciRaj1992 



















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Output:


2











    

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