Check for Children Sum Property in a Binary Tree

Sum.java

// Given a binary tree, write a function that returns true if the tree satisfies below property.
// For every node, data value must be equal to sum of data values in left and right children. Consider data value as 0 for NULL children. 

class Node {

    int data;
    Node left, right;

    public Node(int item) {
        data = item;
        left = right = null;
    }
}

class BinaryTree {

    Node root;

    public void checkSum() {
      System.out.println(" Result " + sum(root));
    }
    
    public int sum(Node root){
        
        if(root==null || (root.left == null && root.right == null)) {
            return 1;
        }
        
        int left  = 0;
        int right = 0;
        
        if(root.left !=null) {
            left = root.left.data;
        }
        
        if(root.right !=null) {
            right = root.right.data;
        }
        
        
        if( (left + right) == root.data && sum(root.left)!=0 && sum(root.right)!=0 ){
            return 1;
        } else{
            return 0;
        }
    }
    
    public static void main(String args[]) {
        
        BinaryTree tree = new BinaryTree();
        tree.root = new Node(10);
        tree.root.left = new Node(8);
        tree.root.right = new Node(2);
        tree.root.left.left = new Node(3);
        tree.root.left.right = new Node(5);
        tree.root.right.left = new Node(2);
        
        tree.checkSum();
    }
}