In this tutorial we shall check if the tree is a sum tree or not.
Problem Statement:
You are given the root node of a binary tree. You need to check if that tree is a sum tree or not.
Example:
Consider the binary tree given below:
In the above image, it is a sum tree.
What is a sum tree?
A tree will be called as sum tree, if the parent node value is equal to the sum of it’s left sub tree and right sub tree.
For 1 and 2 parent node value is 3. That is the sum of 1 + 2
For 4 and 5 parent node value is 9, that is the sum of 4 + 5
For the root node value is 24, i.e it’s sum of left sub tree 3 + 2 + 1 = 6
and sum of right sub tree i.e 9 + 4 + 5 = 18.
By looking at the image, we can infer that, only the leaf node will not satisfy this condition.
But all the internal nodes need to satisfy this condition.