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Commit c4fcc8c

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Threaded tree in Java
1 parent 3605a11 commit c4fcc8c

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3 files changed

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3 files changed

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‎Trees/threadedtree/Demo.java

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/*
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Copyright (C) Deepali Srivastava - All Rights Reserved
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This code is part of DSA course available on CourseGalaxy.com
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*/
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package threadedtree;
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import java.util.Scanner;
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public class Demo
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{
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public static void main(String[] args)
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{
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ThreadedBinaryTree tree = new ThreadedBinaryTree();
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int choice,x;
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Scanner scan = new Scanner(System.in);
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while(true)
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{
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System.out.println("1.Insert a new node");
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System.out.println("2.Delete a node");
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System.out.println("3.Inorder Traversal");
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System.out.println("4.Exit");
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System.out.print("Enter your choice : ");
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choice = scan.nextInt();
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if(choice == 4)
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break;
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switch( choice )
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{
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case 1:
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System.out.print("Enter the key to be inserted : ");
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x = scan.nextInt();
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tree.insert(x);
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break;
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case 2:
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System.out.print("Enter the key to be deleted : ");
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x = scan.nextInt();
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tree.delete(x);
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break;
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case 3:
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tree.inorder();
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break;
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}
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}
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scan.close();
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}
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}

‎Trees/threadedtree/Node.java

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/*
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Copyright (C) Deepali Srivastava - All Rights Reserved
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This code is part of DSA course available on CourseGalaxy.com
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*/
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package threadedtree;
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public class Node
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{
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public Node left;
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public boolean leftThread;
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public int info;
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public boolean rightThread;
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public Node right;
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public Node(int i)
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{
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info = i;
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left = null;
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right = null;
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leftThread = true;
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rightThread = true;
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}
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}
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/*
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Copyright (C) Deepali Srivastava - All Rights Reserved
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This code is part of DSA course available on CourseGalaxy.com
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*/
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package threadedtree;
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public class ThreadedBinaryTree
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{
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private Node root;
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public ThreadedBinaryTree()
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{
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root = null;
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}
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public boolean isEmpty()
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{
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return (root == null);
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}
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private Node inorderPredecessor(Node p)
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{
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if(p.leftThread == true)
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return p.left;
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else
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{
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p=p.left;
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while(p.rightThread == false)
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p=p.right;
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return p;
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}
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}
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private Node inorderSuccessor(Node p)
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{
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if(p.rightThread == true)
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return p.right;
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else
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{
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p=p.right;
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while(p.leftThread==false)
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p=p.left;
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return p;
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}
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}
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public void inorder()
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{
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if(root == null )
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{
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System.out.print("Tree is empty");
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return;
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}
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/*Find the leftmost node of the tree*/
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Node p = root;
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while( p.leftThread == false )
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p = p.left;
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while( p!=null )
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{
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System.out.print(p.info + " ");
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if (p.rightThread == true)
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p = p.right;
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else
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{
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p = p.right;
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while (p.leftThread == false)
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p = p.left;
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}
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}
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System.out.println();
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}
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public void insert(int x)
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{
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Node p = root;
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Node par = null;
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while (p!=null)
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{
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par = p;
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if (x < p.info)
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{
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if (p.leftThread == false)
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p = p.left;
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else
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break;
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}
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else if(x > p.info)
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{
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if (p.rightThread == false)
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p = p.right;
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else
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break;
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}
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else
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{
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System.out.println(x + " already present in the tree");
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return;
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}
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}
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Node temp = new Node(x);
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if (par == null)
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{
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root = temp;
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}
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else if (x < par.info) /*inserted as left child*/
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{
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temp.left = par.left;
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temp.right = par;
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par.leftThread = false;
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par.left = temp;
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}
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else /*inserted as right child*/
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{
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temp.left = par;
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temp.right = par.right;
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par.rightThread = false;
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par.right = temp;
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}
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}
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public void delete(int x)
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{
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Node p = root;
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Node par = null;
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while (p != null)
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{
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if (x == p.info)
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break;
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par = p;
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if (x < p.info)
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{
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if (p.leftThread == false)
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p = p.left;
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else
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break;
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}
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else
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{
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if (p.rightThread == false)
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p = p.right;
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else
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break;
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}
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}
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if (p == null || p.info != x)
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{
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System.out.println(x + " not found");
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return;
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}
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if (p.leftThread == false && p.rightThread == false)/*Case C: 2 children*/
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{
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/*Find inorder successor and its parent*/
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Node ps = p;
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Node s = p.right;
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while (s.leftThread == false)
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{
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ps = s;
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s = s.left;
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}
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p.info = s.info;
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p = s;
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par = ps;
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}
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/*Case A : No child*/
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if (p.leftThread == true && p.rightThread == true)
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{
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if (par == null)
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root = null;
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else if (p == par.left)
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{
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par.leftThread = true;
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par.left = p.left;
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}
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else
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{
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par.rightThread = true;
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par.right = p.right;
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}
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return;
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}
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/*Case B : 1 child*/
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Node ch;
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if (p.leftThread == false) /*node to be deleted has left child */
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ch = p.left;
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else /*node to be deleted has right child */
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ch = p.right;
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if (par == null) /*node to be deleted is root node*/
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root = ch;
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else if (p == par.left)/*node is left child of its parent*/
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par.left = ch;
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else /*node is right child of its parent*/
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par.right = ch;
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Node pred = inorderPredecessor(p);
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Node succ = inorderSuccessor(p);
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if (p.leftThread == false) /*if p has left child, right is a thread */
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pred.right = succ;
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else /*p has right child,left is a thread*/
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succ.left = pred;
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}
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}

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