# Python Program to Find the Sum of All Nodes in a Tree

This python program calculates the sum of all nodes in a binary tree. Binary trees are hierarchical data structures commonly used in computer science to represent hierarchical relationships.

## Problem statement

Given a binary tree, the task is to find the sum of all nodes present in the tree in python.

## Python Program to Find the Sum of All Nodes in a Tree

```class TreeNode:
def __init__(self, value):
self.value = value
self.left = None
self.right = None

def sum_of_nodes(root):
if root is None:
return 0

return root.value + sum_of_nodes(root.left) + sum_of_nodes(root.right)
root = TreeNode(5)
root.left = TreeNode(3)
root.right = TreeNode(8)
root.left.left = TreeNode(1)
root.left.right = TreeNode(4)
root.right.left = TreeNode(6)
root.right.right = TreeNode(9)

total_sum = sum_of_nodes(root)
print("Sum of all nodes in the tree:", total_sum)
```

## How it works

1. Node Definition: We define a class `TreeNode` representing a node in the binary tree. Each node contains a value and references to its left and right children.
2. Sum Calculation: We define a recursive function `sum_of_nodes(root)` that takes the root of the tree as its parameter and returns the sum of all node values in the tree.
3. Calculating the Sum: We call the `sum_of_nodes` function with the root of our example tree to calculate the sum of all node values: total_sum = sum_of_nodes(root) print(“Sum of all nodes in the tree:”, total_sum)