Start with the tree.java program and modify it to create a binary tree from a string of letters (like A, B, and so on) entered by the user. Each letter will be displayed in its own node. Construct the tree so that all the nodes that contain letters are leaves. Parent nodes can contain some non-letter symbol like +. Make sure that every parent node has exactly two children. Dont worry if the tree is unbalanced. Note that this will not be a search tree; theres no quick way to find a given node.

// tree.java

// demonstrates binary tree

// to run this program: C>java TreeApp

import java.io.*;

import java.util.*; // for Stack class

////////////////////////////////////////////////////////////////

class Node

{

public int iData; // data item (key)

public double dData; // data item

public Node leftChild; // this node's left child

public Node rightChild; // this node's right child

public void displayNode() // display ourself

{

System.out.print('{');

System.out.print(iData);

System.out.print(", ");

System.out.print(dData);

System.out.print("} ");

}

} // end class Node

////////////////////////////////////////////////////////////////

class Tree

{

private Node root; // first node of tree

// -------------------------------------------------------------

public Tree() // constructor

{ root = null; } // no nodes in tree yet

// -------------------------------------------------------------

public Node find(int key) // find node with given key

{ // (assumes non-empty tree)

Node current = root; // start at root

while(current.iData != key) // while no match,

{

if(key < current.iData) // go left?

current = current.leftChild;

else // or go right?

current = current.rightChild;

if(current == null) // if no child,

return null; // didn't find it

}

return current; // found it

} // end find()

// -------------------------------------------------------------

public void insert(int id, double dd)

{

Node newNode = new Node(); // make new node

newNode.iData = id; // insert data

newNode.dData = dd;

if(root==null) // no node in root

root = newNode;

else // root occupied

{

Node current = root; // start at root

Node parent;

while(true) // (exits internally)

{

parent = current;

if(id < current.iData) // go left?

{

current = current.leftChild;

if(current == null) // if end of the line,

{ // insert on left

parent.leftChild = newNode;

return;

}

} // end if go left

else // or go right?

{

current = current.rightChild;

if(current == null) // if end of the line

{ // insert on right

parent.rightChild = newNode;

return;

}

} // end else go right

} // end while

} // end else not root

} // end insert()

// -------------------------------------------------------------

public boolean delete(int key) // delete node with given key

{ // (assumes non-empty list)

Node current = root;

Node parent = root;

boolean isLeftChild = true;

while(current.iData != key) // search for node

{

parent = current;

if(key < current.iData) // go left?

{

isLeftChild = true;

current = current.leftChild;

}

else // or go right?

{

isLeftChild = false;

current = current.rightChild;

}

if(current == null) // end of the line,

return false; // didn't find it

} // end while

// found node to delete

// if no children, simply delete it

if(current.leftChild==null &&

current.rightChild==null)

{

if(current == root) // if root,

root = null; // tree is empty

else if(isLeftChild)

parent.leftChild = null; // disconnect

else // from parent

parent.rightChild = null;

}

// if no right child, replace with left subtree

else if(current.rightChild==null)

if(current == root)

root = current.leftChild;

else if(isLeftChild)

parent.leftChild = current.leftChild;

else

parent.rightChild = current.leftChild;

// if no left child, replace with right subtree

else if(current.leftChild==null)

if(current == root)

root = current.rightChild;

else if(isLeftChild)

parent.leftChild = current.rightChild;

else

parent.rightChild = current.rightChild;

else // two children, so replace with inorder successor

{

// get successor of node to delete (current)

Node successor = getSuccessor(current);

// connect parent of current to successor instead

if(current == root)

root = successor;

else if(isLeftChild)

parent.leftChild = successor;

else

parent.rightChild = successor;

// connect successor to current's left child

successor.leftChild = current.leftChild;

} // end else two children

// (successor cannot have a left child)

return true; // success

} // end delete()

// -------------------------------------------------------------

// returns node with next-highest value after delNode

// goes to right child, then right child's left descendents

private Node getSuccessor(Node delNode)

{

Node successorParent = delNode;

Node successor = delNode;

Node current = delNode.rightChild; // go to right child

while(current != null) // until no more

{ // left children,

successorParent = successor;

successor = current;

current = current.leftChild; // go to left child

}

// if successor not

if(successor != delNode.rightChild) // right child,

{ // make connections

successorParent.leftChild = successor.rightChild;

successor.rightChild = delNode.rightChild;

}

return successor;

}

// -------------------------------------------------------------

public void traverse(int traverseType)

{

switch(traverseType)

{

case 1: System.out.print(" Preorder traversal: ");

preOrder(root);

break;

case 2: System.out.print(" Inorder traversal: ");

inOrder(root);

break;

case 3: System.out.print(" Postorder traversal: ");

postOrder(root);

break;

}

System.out.println();

}

// -------------------------------------------------------------

private void preOrder(Node localRoot)

{

if(localRoot != null)

{

System.out.print(localRoot.iData + " ");

preOrder(localRoot.leftChild);

preOrder(localRoot.rightChild);

}

}

// -------------------------------------------------------------

private void inOrder(Node localRoot)

{

if(localRoot != null)

{

inOrder(localRoot.leftChild);

System.out.print(localRoot.iData + " ");

inOrder(localRoot.rightChild);

}

}

// -------------------------------------------------------------

private void postOrder(Node localRoot)

{

if(localRoot != null)

{

postOrder(localRoot.leftChild);

postOrder(localRoot.rightChild);

System.out.print(localRoot.iData + " ");

}

}

// -------------------------------------------------------------

public void displayTree()

{

Stack globalStack = new Stack();

globalStack.push(root);

int nBlanks = 32;

boolean isRowEmpty = false;

System.out.println(

"......................................................");

while(isRowEmpty==false)

{

Stack localStack = new Stack();

isRowEmpty = true;

for(int j=0; j

System.out.print(' ');

while(globalStack.isEmpty()==false)

{

Node temp = (Node)globalStack.pop();

if(temp != null)

{

System.out.print(temp.iData);

localStack.push(temp.leftChild);

localStack.push(temp.rightChild);

if(temp.leftChild != null ||

temp.rightChild != null)

isRowEmpty = false;

}

else

{

System.out.print("--");

localStack.push(null);

localStack.push(null);

}

for(int j=0; j

System.out.print(' ');

} // end while globalStack not empty

System.out.println();

nBlanks /= 2;

while(localStack.isEmpty()==false)

globalStack.push( localStack.pop() );

} // end while isRowEmpty is false

System.out.println(

"......................................................");

} // end displayTree()

// -------------------------------------------------------------

} // end class Tree

////////////////////////////////////////////////////////////////

class TreeApp

{

public static void main(String[] args) throws IOException

{

int value;

Tree theTree = new Tree();

theTree.insert(50, 1.5);

theTree.insert(25, 1.2);

theTree.insert(75, 1.7);

theTree.insert(12, 1.5);

theTree.insert(37, 1.2);

theTree.insert(43, 1.7);

theTree.insert(30, 1.5);

theTree.insert(33, 1.2);

theTree.insert(87, 1.7);

theTree.insert(93, 1.5);

theTree.insert(97, 1.5);

while(true)

{

System.out.print("Enter first letter of show, ");

System.out.print("insert, find, delete, or traverse: ");

int choice = getChar();

switch(choice)

{

case 's':

theTree.displayTree();

break;

case 'i':

System.out.print("Enter value to insert: ");

value = getInt();

theTree.insert(value, value + 0.9);

break;

case 'f':

System.out.print("Enter value to find: ");

value = getInt();

Node found = theTree.find(value);

if(found != null)

{

System.out.print("Found: ");

found.displayNode();

System.out.print(" ");

}

else

System.out.print("Could not find ");

System.out.print(value + ' ');

break;

case 'd':

System.out.print("Enter value to delete: ");

value = getInt();

boolean didDelete = theTree.delete(value);

if(didDelete)

System.out.print("Deleted " + value + ' ');

else

System.out.print("Could not delete ");

System.out.print(value + ' ');

break;

case 't':

System.out.print("Enter type 1, 2 or 3: ");

value = getInt();

theTree.traverse(value);

break;

default:

System.out.print("Invalid entry ");

} // end switch

} // end while

} // end main()

// -------------------------------------------------------------

public static String getString() throws IOException

{

InputStreamReader isr = new InputStreamReader(System.in);

BufferedReader br = new BufferedReader(isr);

String s = br.readLine();

return s;

}

// -------------------------------------------------------------

public static char getChar() throws IOException

{

String s = getString();

return s.charAt(0);

}

//-------------------------------------------------------------

public static int getInt() throws IOException

{

String s = getString();

return Integer.parseInt(s);

}

// -------------------------------------------------------------

} // end class TreeApp

////////////////////////////////////////////////////////////////