# Convert binary tree to its Sum tree

**Objective: **Given a binary tree, write an algorithm to convert it into its Sum tree.

**What is Sum tree: ***Sum tree of a binary tree, is a tree where each node in the converted tree will contains the sum of the left and right sub trees in the original tree. *

**Example:**

**Approach:**

- Recursively calculate the left sum from left sum tree.
- Recursively calculate the right sum from right tree.
- prepare the
.*return root.data + left sum + right sum* - Update the root data as
*root.data = left sum + right sum.* - update the newRoot = root.
- See the code for better understanding.

**Complete Code:**

**Output**:

Original Tree: -2 -1 4 5 -6 3 10 Sum tree: 0 2 0 8 0 4 0

why do u need to set the newRoot in line13? you are not changing any node pointers in the SumTree method. looks like an unnecessary line of code that really does nothing.

I agree. Its not required at all.