BinaryTreess.java

//binary tree

import java.util.*;

public class BinaryTreess {
    static class Node{
        int data;
        Node left;
        Node right;

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

    static class BinaryTree{
        static int idx=-1;
        public static Node buildTree(int nodes[]){

            idx++;
            if(nodes[idx]==-1){
                return null;
            }

            Node newNode=new Node(nodes[idx]);
            newNode.left=buildTree(nodes);
            newNode.right=buildTree(nodes);

            return newNode;

        }
    }

    public static void preOrder(Node root){
        if(root==null){
            return;
        }
          System.out.print(root.data + " ");
          preOrder(root.left);
          preOrder(root.right);
    }

    public static void inOrder(Node root){
        if(root==null){
            return;
        }

        inOrder(root.left);
        System.out.print(root.data + " ");
        inOrder(root.right);
    }

    public static void postOrder(Node root){
        if(root==null){
            return;
        }

        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.data + " ");
    }
    
    public static void levelOrder(Node root){
        if(root==null){
            return;
        }

           Queue<Node>q=new LinkedList<>();

           q.add(root);
           q.add(null);

           while(!q.isEmpty()){
            Node currNode=q.remove();
            if(currNode==null){
                System.out.println();
                if(q.isEmpty()){
                    break;
                }else{
                    q.add(null);
                }
            }else{
                System.out.print(currNode.data + " ");
                if(currNode.left!=null){
                    q.add(currNode.left);
                }
                if(currNode.right!=null){
                    q.add(currNode.right);
                }
            }
           }

    }

    public static int countOfNodes(Node root){

        if(root==null){
            return 0;
        }
              
        int leftNodes=countOfNodes(root.left);
        int rightNodes=countOfNodes(root.right);
        

        return leftNodes+rightNodes+1;
    }

    public static int sumOfNodes(Node root){

        if(root==null){
            return 0;
        }
              
        int leftSum=sumOfNodes(root.left);
        int rightSum=sumOfNodes(root.right);

        return leftSum+rightSum+root.data;
    }


    public static void main(String[] args) {
        int nodes[]={1,3,4,-1,-1,5,-1,-1,3,-1,6,-1,-1};
        BinaryTree tree=new BinaryTree();
        Node root=tree.buildTree(nodes);
        
        System.out.print("PreOrder Traversal :" + " " );
        preOrder(root);

        System.out.println();
        System.out.print("InOrder Traversal :" + " " );
        inOrder(root);

        System.out.println();
        System.out.print("PostOrder Traversal :" + " " );
        postOrder(root);

        System.out.println();

        levelOrder(root);

        System.out.println(countOfNodes(root));

        System.out.println(sumOfNodes(root));
    }
}