import java.util.*; 
 
public class BinarySearchTree 
{ 
 class Node 
 {  int key; 
  Node left, right; 
   
  public Node(int data) 
  {  key = data; 
   left = right = null; 
  } 
 } 
   
 private Node root; 
  
 public BinarySearchTree() 
 { root=null; } 
 
 public void insert(int data) 
 {  root = insertRec(root, data); } 
  
 private Node insertRec(Node root,int key) 
 {  if (root == null)  
  { root = new Node(key); 
   return root; 
  }   
  if (key < root.key)   
   root.left = insertRec(root.left, key); 
  else if (key > root.key)  
   root.right = insertRec(root.right, key); 
 
  return root; 
 } 
  
 public void inorder() 
 { inorderRec(root); }  
  
 private void inorderRec(Node root) 
 { 
  if (root != null) { 
  inorderRec(root.left); 
  System.out.print(root.key + " "); 
  inorderRec(root.right); 
  } 
 } 
  
  
 
 
 
 
public void preorder() 
 {   preorderrec(root);  } 
  
 private void preorderrec(Node node) 
 { 
  if (node == null) 
   return; 
  System.out.print(node.key + " "); 
  preorderrec(node.left); 
  preorderrec(node.right); 
 } 
  
 public void postorder() 
 {   postorderrec(root); } 
  
 private void postorderrec(Node node) 
 { 
  if (node == null) 
   return; 
  postorderrec(node.left); 
  postorderrec(node.right); 
  System.out.print(node.key + " "); 
 } 
  
 public static void main(String[] args)  
 { 
  Scanner sc = new Scanner(System.in); 
  BinarySearchTree bst = new BinarySearchTree(); 
  String ch=""; 
  do{ 
  System.out.print("Enter the element to be inserted in the tree: "); 
   int n=sc.nextInt(); 
   sc.nextLine(); 
    
   bst.insert(n); 
 System.out.print("Do you want to insert another element? (Say 'yes'): "); 
   ch = sc.nextLine(); 
  }while(ch.equals("yes")); 
   
 System.out.print("Inorder Traversal : The elements in the tree are: "); 
  bst.inorder(); 
  System.out.println();  
 System.out.print("Preorder Traversal : The elements in the tree are: "); 
  bst.preorder(); 
  System.out.println();   
 System.out.print("Postorder Traversal : The elements in the tree are: "); 
  bst.postorder(); 
  System.out.println(); 
 } 
}

OUTPUT:

Enter the element to be inserted in the tree: 50
Do you want to insert another element? (Say 'yes'): yes
Enter the element to be inserted in the tree: 30
Do you want to insert another element? (Say 'yes'): yes
Enter the element to be inserted in the tree: 20
Do you want to insert another element? (Say 'yes'): yes
Enter the element to be inserted in the tree: 40
Do you want to insert another element? (Say 'yes'): yes
Enter the element to be inserted in the tree: 70
Do you want to insert another element? (Say 'yes'): yes
Enter the element to be inserted in the tree: 60
Do you want to insert another element? (Say 'yes'): yes
Enter the element to be inserted in the tree: 80
Do you want to insert another element? (Say 'yes'): no
Inorder Traversal : The elements in the tree are: 20 30 40 50 60 70 80 
Preorder Traversal : The elements in the tree are: 50 30 20 40 70 60 80 
Postorder Traversal : The elements in the tree are: 20 40 30 60 80 70 50