Check if a given Binary Tree is SumTree

PROBLEM :

Write a function that returns true if the given Binary Tree is SumTree else false. A SumTree is a Binary Tree where the value of a node is equal to sum of the nodes present in its left subtree and right subtree. An empty tree is SumTree and sum of an empty tree can be considered as 0. A leaf node is also considered as SumTree.

Following is an example of SumTree.

          26
        /    \
    10      3
    /   \   /   \
 4     6  1    2


Input:

The task is to complete the method which takes one argument, root of Binary Tree. There are multiple test cases. For each test case, this method will be called individually.

Output:
The function should return true if passed tree is Sum Tree, else false

Constraints:
1 <=T<= 30
1 <=Number of nodes<= 100
1 <=Data of a node<= 1000


--------------------------------------------------------------------------------
SIMPLE c++ IMPLEMENTATION :
--------------------------------------------------------------------------------

/*  Tree node
struct Node
{
    int data;
    struct Node* left, * right;
}; */
// Should return true if tree is Sum Tree, else false


int sum(struct Node*) ;

bool isSumTree(struct Node* root)
{
     if(root==NULL)
     return true ;
     if(root->left==NULL&&root->right==NULL)
     return true ;
   
     int L,R ;
   
     L=sum(root->left) ;
     R=sum(root->right) ;
   
     if(root->data==L+R&&isSumTree(root->left)&&isSumTree(root->right))
     {
            return true ;
     }
     else
        return false ;
       
}

int sum(struct Node *root)
{
    if(root==NULL)
    return 0 ;
    else
        return(sum(root->left)+root->data+sum(root->right)) ;
}

---------------------------------------------------------------------------------