Sum Tree.java

// { Driver Code Starts
//Initial Template for Java

import java.util.LinkedList; 
import java.util.Queue; 
import java.io.*;
import java.util.*;

class Node{
    int data;
    Node left;
    Node right;
    Node(int data){
        this.data = data;
        left=null;
        right=null;
    }
}

class GfG {
    
    static Node buildTree(String str){
        
        if(str.length()==0 || str.charAt(0)=='N'){
            return null;
        }
        
        String ip[] = str.split(" ");
        // Create the root of the tree
        Node root = new Node(Integer.parseInt(ip[0]));
        // Push the root to the queue
        
        Queue<Node> queue = new LinkedList<>(); 
        
        queue.add(root);
        // Starting from the second element
        
        int i = 1;
        while(queue.size()>0 && i < ip.length) {
            
            // Get and remove the front of the queue
            Node currNode = queue.peek();
            queue.remove();
                
            // Get the current node's value from the string
            String currVal = ip[i];
                
            // If the left child is not null
            if(!currVal.equals("N")) {
                    
                // Create the left child for the current node
                currNode.left = new Node(Integer.parseInt(currVal));
                // Push it to the queue
                queue.add(currNode.left);
            }
                
            // For the right child
            i++;
            if(i >= ip.length)
                break;
                
            currVal = ip[i];
                
            // If the right child is not null
            if(!currVal.equals("N")) {
                    
                // Create the right child for the current node
                currNode.right = new Node(Integer.parseInt(currVal));
                    
                // Push it to the queue
                queue.add(currNode.right);
            }
            i++;
        }
        
        return root;
    }
    
	public static void main (String[] args) throws IOException{
	        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
	        
	        int t=Integer.parseInt(br.readLine());
    
	        while(t > 0){
	            String s = br.readLine();
    	    	Node root = buildTree(s);
        	    Tree g = new Tree();
			
			    if(g.isSumTree(root) == true)
    			    System.out.println(1);
    			else 
    			    System.out.println(0);
                t--;
            
        }
    }
  
}

// } Driver Code Ends


/* A Binary Tree node
class Node
{
    int data;
    Node left, right;

    Node(int item)
    {
        data = item;
        left = right = null;
    }
}
*/
class Tree
{
	boolean isSumTree(Node root)
	{
        if(root==null || isLeaf(root))
            return true;
        
        int ls,rs;
        if(isSumTree(root.left) && isSumTree(root.right))
        {
            if(root.left==null)
                ls = 0;
            else if(isLeaf(root.left))
                ls = root.left.data;
            else
                ls = 2*(root.left.data);
            
            if(root.right==null)
                rs = 0;
            else if(isLeaf(root.right))
                rs = root.right.data;
            else
                rs = 2*(root.right.data);
            
            if(root.data == (rs+ls))
                return true;
            
            
                
        }
        return false;
             
	}
	boolean isLeaf(Node root)
    {
        if(root==null)
            return false;
        if(root.left==null && root.right == null)
            return true;
        else 
            return false;
    }
}