Sum of all nodes in a binary tree

using System;

// C# Program to print sum of 
// all the elements of a binary tree 
public class GFG
{
public class Node
{
    public int key;
    public Node left, right;
}

/* utility that allocates a new  
   Node with the given key */
public static Node newNode(int key)
{
    Node node = new Node();
    node.key = key;
    node.left = node.right = null;
    return (node);
}

/* Function to find sum  
   of all the elements*/
public static int addBT(Node root)
{
    if (root == null)
    {
        return 0;
    }
    return (root.key + addBT(root.left) + addBT(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);
    root.right.left = newNode(6);
    root.right.right = newNode(7);
    root.right.left.right = newNode(8);

    int sum = addBT(root);
    Console.WriteLine("Sum of all the elements is: " + sum);
}
}

// This code is contributed by Shrikant13

// C# Program to print sum of
// all the elements of a binary tree

using System;
using System.Collections.Generic;

public class GFG {
    public class Node {
        public int key;
        public Node left, right;
    }

    // Utility function to create a new node
    public static Node newNode(int key)
    {
        Node node = new Node();
        node.key = key;
        node.left = node.right = null;
        return (node);
    }

    /*Function to find sum of all elements*/
    public static int sumBT(Node root)
    {
        // sum variable to track the sum of
        // all variables.
        int sum = 0;

        Queue<Node> q = new Queue<Node>();

        // Pushing the first level.
        q.Enqueue(root);

        // Pushing elements at each level from
        // the tree.
        while (q.Count!=0) {
            Node temp = q.Dequeue();

            // After popping each element from queue
            // add its data to the sum variable.
            sum += temp.key;

            if (temp.left != null) {
                q.Enqueue(temp.left);
            }
            if (temp.right != null) {
                q.Enqueue(temp.right);
            }
        }
        return sum;
    }

    // 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);
        root.right.left = newNode(6);
        root.right.right = newNode(7);
        root.right.left.right = newNode(8);

        Console.WriteLine("Sum of all elements in the binary tree is: "
                          + sumBT(root));
    }
}

// This code is contributed by Abhijeet Kumar(abhijeet19403)

using System;

// Definition of a binary tree node
public class Node
{
    public int val;
    public Node left;
    public Node right;

    public Node(int v)
    {
        val = v;
        left = null;
        right = null;
    }
}

public class MorrisTraversal
{
    // Morris Traversal function to find the sum of all nodes in
    // a binary tree
    public static long SumBT(Node root)
    {
        long sum = 0;
        while (root != null)
        {
            if (root.left == null)
            {
                // If there is no left child, add
                // the value of the current node
                // to the sum and move to the
                // right child
                sum += root.val;
                root = root.right;
            }
            else
            {// If there is a left child
                Node prev = root.left;
              
                // Find the rightmost node
                // in the left subtree of
                // the current node
                while (prev.right != null && prev.right != root)
                {
                    prev = prev.right;
                }
                
                // If the right child of the
                // rightmost node is null, set
                // it to the current node and
                // move to the left child
                if (prev.right == null)
                {   
                    prev.right = root;
                    root = root.left;
                }
              
                // If the right child of the rightmost
                // node is the current node, set it to
                // null, add the value of the current
                // node to the sum and move to the right
                // child
                else
                {
                    prev.right = null;
                    sum += root.val;
                    root = root.right;
                }
            }
        }
        return sum;
    }

    // Driver code
    public static void Main(string[] args)
    {
        // Example binary tree:    1
        //                        / \
        //                       2   3
        //                      / \   
        //                     4   5
        Node root = new Node(1);
        root.left = new Node(2);
        root.right = new Node(3);
        root.left.left = new Node(4);
        root.left.right = new Node(5);

        // Find the sum of all nodes in the binary tree
        long sum = SumBT(root);
        Console.WriteLine("Sum of all nodes in the binary tree is " + sum);

        // Clean up memory (optional)
        root = null;

        // Prevent the console window from closing immediately
        Console.ReadLine();
    }
}
// This code is contributed by rambabuguphka