DS: Binary Tree Program

import java.util.Scanner;

public class BTree {
public static void main(String args[]) {

List c = new List();
int d;
Scanner s = new Scanner(System.in);
do {
System.out.println("Binary tree operations");
System.out.println("1.create()");
System.out.println("2.inorder()");
System.out.println("3.preorder()");
System.out.println("4.postorder()");
System.out.println("5.empty()");
System.out.println("Enter ur choice");
d = s.nextInt();
switch (d) {
case 1:
c.create();
break;
case 2:
c.inorder(c.root);
break;
case 3:
c.preorder(c.root);
break;
case 4:
c.postorder(c.root);
break;
case 5:
if (c.isempty())
System.out.println("BTree is empty");
else
System.out.println("BTree is not empty");
break;

}

} while (d < 6);

}

}

class Node {
Object data;
Node left;
Node right;
}

class List {
Node s[] = new Node[10];
int top;
Object value;
Node root;
Node p, temp;
Scanner sc = new Scanner(System.in);

public List() {
top = 0;
s[top] = null;

}

public boolean isempty() {
return root == null;

}

public void create() {
root = new Node();
System.out.println("Enter a value");
Object value;
value = sc.nextInt();
String ch;
root.data = value;
p = root;
while (p != null) {
System.out.println("The right child" + p.data + "is exists");
ch = sc.next();
if (ch.equals("n"))
p.right = null;
else {
temp = new Node();
System.out.println("Enter a value");
value = sc.nextInt();
temp.data = value;
p.right = temp;
push(temp);

}
System.out.println("The left child of " + p.data + "is exists");
ch = sc.next();
if (ch.equals("n")) {
p.left = null;
p = pop();
} else {
temp = new Node();
System.out.println("Enter a value");
value = sc.nextInt();
temp.data = value;
p.left = temp;
p = temp;
}
}

}

public void push(Node value) {
if (top == s.length - 1) {
System.out.println("Stack is overflow");
return;

} else
s[++top] = value;

}

public Node pop() {
if (top == -1) {
System.out.println("Stack is underflow");
return null;
}
Node x = s[top--];
return x;
}

public void inorder(Node p) {
if (p != null) {

inorder(p.left);
System.out.print(p.data + " ");
inorder(p.right);
}

}

public void preorder(Node p) {
if (p != null) {

System.out.print(p.data + " ");
preorder(p.left);
preorder(p.right);

}

}

public void postorder(Node p) {
if (p != null) {

postorder(p.left);
postorder(p.right);
System.out.print(p.data + " ");

}

}

}

Output:

 Binary tree operations

1.create()

2.inorder() 

3.preorder()

4.postorder()

5.empty() 

Enter ur choice

 1

Enter a value

10   

The right child10is exists

Y

 Enter a value

20

The left child of 10is exists

Y

 Enter a value   

 30

 The right child30is exists

 Y

 Enter a value 

 40   

The left child of 30is exists             

n

The right child40is exists

n

The left child of 40is exists

n 

The right child20is exists

n  

The left child of 20is exists

n

                                                                                                                                                      Binary tree operations                                                       

1.create()

2.inorder()

3.preorder()

4.postorder()

5.empty() 

Enter ur choice

 2

The  inorder is =30 ,40, 10, 20,

Binary tree operations

1.create()

2.inorder()

3.preorder() 

4.postorder()

5.empty() 

Enter ur choice

3

The preorder is=10 30 40 20

Binary tree operations

1.create()

2.inorder()

3.preorder()

4.postorder()

5.empty()

Enter ur choice 

4

The post order is=40 30 20 10

Binary tree operations

1.create()

2.inorder()

3.preorder()

4.postorder()

5.empty()

Enter ur choice

5

BTree is not empty

Binary tree operations

1.create()

2.inorder()

3.preorder()

4.postorder()

5.empty()

Enter ur choice

6