Question

Create a new Java Application that has the following methods:

1. A method that generate a binary search tree (BST) where the number of nodes and the range of the

   values are from a file.

2. A recursive method to print the BST in preorder traversal

3. A recursive method to print the BST in post-order traversal

4. A recursive method to print the BST in in-order traversal

5. A recursive method to count the number of all nodes in BST

6. A method to find the largest value in a BST

7. A method to find and return the smallest value in a BST.

8. A method to search for a given value V in a BST.

9. A method to print ancestors of a given value V

10. A method to count the number of comparisons to decide whether a given value V is in a BST.

11. A method to count the number of leaf nodes in BST

12. A method to count the number of nodes that contain even numbers in a BST

13. A method to count the number of nodes with 2 children (child may be a single node or a sub-tree)

14. A method to print a BST sorted in reverse order

15. A method to print a BST in breadth first order

16. A method to check if two BSTs are identical

17. A method mirror () to create a mirror image of BST

18. A method to check if a BST T1 is a mirror of T2

19. A method to find the common elements between two BSTs, and insert them in 3rd BST

Write the main method to test these methods described in 1 to 19

Answer 1

import java.util.Scanner;
class BSTNode
{
BSTNode left, right;
int data;
public BSTNode()
{
left = null;
right = null;
data = 0;
}
public BSTNode(int n)
{
left = null;
right = null;
data = n;
}
public void setLeft(BSTNode n)
{
left = n;
}
public void setRight(BSTNode n)
{
right = n;
}
public BSTNode getLeft()
{
return left;
}
public BSTNode getRight()
{
return right;
}
public void setData(int d)
{
data = d;
}
public int getData()
{
return data;
}
}
class BST
{
private BSTNode root;
public BST()
{
root = null;
}
public boolean isEmpty()
{
return root == null;
}
public void insert(int data)
{
root = insert(root, data);
}
private BSTNode insert(BSTNode node, int data)
{
if (node == null)
node = new BSTNode(data);
else
{
if (data <= node.getData())
node.left = insert(node.left, data);
else
node.right = insert(node.right, data);
}
return node;
}

public BSTNode insertFromFile(String filename)
{
Scanner scanner = new Scanner(new.File(filename));
while(scanner.hasNextInt())
{
root =insert(root,scanner.nextInt());
}
}

public void delete(int k)
{
if (isEmpty())
System.out.println("Tree Empty");
else if (search(k) == false)
System.out.println("Sorry "+ k +" is not present");
else
{
root = delete(root, k);
System.out.println(k+ " deleted from the tree");
}
}
private BSTNode delete(BSTNode root, int k)
{
BSTNode p, p2, n;
if (root.getData() == k)
{
BSTNode lt, rt;
lt = root.getLeft();
rt = root.getRight();
if (lt == null && rt == null)
return null;
else if (lt == null)
{
p = rt;
return p;
}
else if (rt == null)
{
p = lt;
return p;
}
else
{
p2 = rt;
p = rt;
while (p.getLeft() != null)
p = p.getLeft();
p.setLeft(lt);
return p2;
}
}
if (k < root.getData())
{
n = delete(root.getLeft(), k);
root.setLeft(n);
}
else
{
n = delete(root.getRight(), k);
root.setRight(n);
}
return root;
}
private int countNodes(BSTNode r)
{
if (r == null)
return 0;
else
{
int l = 1;
l += countNodes(r.getLeft());
l += countNodes(r.getRight());
return l;
}
}
public boolean search(int val)
{
return search(root, val);
}
private boolean search(BSTNode r, int val)
{
boolean found = false;
while ((r != null) && !found)
{
int rval = r.getData();
if (val < rval)
r = r.getLeft();
else if (val > rval)
r = r.getRight();
else
{   
found = true;
break;
}
found = search(r, val);
}   
return found;
}
public void inorder()
{
inorder(root);
}
private void inorder(BSTNode r)
{
if (r != null)
{
inorder(r.getLeft());
System.out.print(r.getData() +" ");
inorder(r.getRight());
}
}
public void preorder()
{
preorder(root);
}
private void preorder(BSTNode r)
{
if (r != null)
{
System.out.print(r.getData() +" ");
preorder(r.getLeft());
preorder(r.getRight());
}
}
public void postorder()
{
postorder(root);
}
private void postorder(BSTNode r)
{
if (r != null)
{
postorder(r.getLeft());
postorder(r.getRight());
System.out.print(r.getData() +" ");
}
}
}
public class BinarySearchTree
{
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
BST bst = new BST();
System.out.println("Binary Search Tree Test\n");
char ch;

insertFromFile("myfile.txt");

do
{
System.out.println("\nBinary Search Tree Operations\n");
System.out.println("1. insert ");
System.out.println("2. delete");
System.out.println("3. search");
System.out.println("4. count nodes");
System.out.println("5. check empty");
int choice = scan.nextInt();
switch (choice)
{
case 1 :
System.out.println("Enter integer element to insert");
bst.insert( scan.nextInt() );
break;
case 2 :
System.out.println("Enter integer element to delete");
bst.delete( scan.nextInt() );
break;
case 3 :
System.out.println("Enter integer element to search");
System.out.println("Search result : "+ bst.search( scan.nextInt() ));
break;
case 4 :
System.out.println("Nodes = "+ bst.countNodes());
break;
case 5 :
System.out.println("Empty status = "+ bst.isEmpty());
break;
default :
System.out.println("Wrong Entry \n ");
break;
}
System.out.print("\nPost order : ");
bst.postorder();
System.out.print("\nPre order : ");
bst.preorder();
System.out.print("\nIn order : ");
bst.inorder();
System.out.println("\nDo you want to continue (Type y or n) \n");
ch = scan.next().charAt(0);
} while (ch == 'Y'|| ch == 'y');
}
}