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Binary Tree Delete Java

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(Binary Tree Delete) In this exercise, we discuss deleting items from binary search trees. The deletion algorithm is not as straightforward as the insertion algorithm. There are three cases that are encountered when deleting an item-the item is contained in a leaf node (i.e., it has no children), the item is contained in a node that has one child or the item is contained in a node that has two children.

If the item to be deleted is contained in a leaf node, the node is deleted and the reference in the parent node is set to null.

If the item to be deleted is contained in a node with one child, the reference in the parent node is set to reference the child node and the node containing the data item is deleted. This causes the child node to take the place of the deleted node in the tree.

The last case is the most difficult. When a node with two children is deleted, another node in the tree must take its place. However, the reference in the parent node cannot simply be assigned to reference one of the children of the node to be deleted. In most cases, the resulting binary search tree would not adhere to the following characteristic of binary search trees (with no duplicate values): The values in any left subtree are less than the value in the parent node, and the values in any right subtree are greater than the value in the parent node.

Which node is used as a replacement node to maintain this characteristic? Either the node containing the largest value in the tree less than the value in the node being deleted, or the node containing the smallest value in the tree greater than the value in the node being deleted. Let us consider the node with the smaller value. In a binary search tree, the largest value less than a parent's value is located in the left subtree of the parent node and is guaranteed to be contained in the rightmost node of the subtree. This node is located by walking down the left subtree to the right until the reference to the right child of the current node is null. We are now referencing the replacement node which is either a leaf node or a node with one child to its left. If the replacement node is a leaf node, the steps to perform the deletion are as follows:
a. Store the reference to the node to be deleted in a temporary reference variable.
b. Set the reference in the parent of the node being deleted to reference the replacement node.
c. Set the reference in the parent of the replacement node to null.
d. Set the reference to the right subtree in the replacement node to reference the right subtree of the node to be deleted.
e. Set the reference to the left subtree in the replacement node to reference the left subtree of the node to be deleted.
The deletion steps for a replacement node with a left child are similar to those for a replacement node with no children, but the algorithm also must move the child into the replacement node's position in the tree. If the replacement node is a node with a left child, the steps to perform the deletion are as follows:
a. Store the reference to the node to be deleted in a temporary reference variable.
b. Set the reference in the parent of the node being deleted to reference the replacement node.
c. Set the reference in the parent of the replacement node reference to the left child of the replacement node.
d. Set the reference to the right subtree in the replacement node reference to the right subtree of the node to be deleted.
e. Set the reference to the left subtree in the replacement node to reference the left subtree of the node to be deleted.
Write method deleteNode, which takes as its argument the value to be deleted. Method deleteNode should locate in the tree the node containing the value to be deleted and use the algorithms discussed here to delete the node. If the value is not found in the tree, the method should print a message that indicates whether or not the value is deleted. Modify the program of Fig. 17.17 and Fig. 17.18 (Tree.java and TreeTest.java) to use this method. After deleting an item, call the methods inorderTraversal, preorderTraversal and postorderTraversal to confirm that the delete operation was performed correctly.

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https://brainmass.com/computer-science/performance-of-systems/129940

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In this exercise, we discuss deleting items from binary search trees. The deletion algorithm is not as straightforward as the insertion algorithm. There are three cases that are encountered when deleting an item-the item is contained in a leaf node (i.e., it has no children), the item is contained in a node that has one child or the item is contained in a node that has two children.

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Java Binary Search Tree Solution

Dear OTA -

I need a Java solution named TestGRE.java with a main method to test a Student Graduate Record Examination Score Managment System using BinarySearchTree java classes.

The solution should use the attached Student class.

Also, sample input that can be used is contained in the attached StudData.dat file.

The TestGRE should return the following when run from the command line:

C:JavaBinSearchTree>java TestGRE
Please Enter a valid FileName: StudData.dat

Choose an operation:
1: contains (string)
2: remove (string)
3: add (string)
4: print (traversal order)
9: stop Testing

Enter choice: 4
Choose a traversal order:
1: Preorder
2: Inorder
3: Postorder
3
The tree in Postorder is:
Brown in NJ earns 89 verbal, and 67 quantitative.
Arnold in VA earns 77 verbal, and 88 quantitative.
Thompson in NY earns 99 verbal, and 99 quantitative.
John in VA earns 89 verbal, and 89 quantitative.
Conner in NY earns 98 verbal, and 100 quantitative.
Smith in MD earns 89 verbal, and 89 quantitative.

Choose an operation:
1: contains (string)
2: remove (string)
3: add (string)
4: print (traversal order)
9: stop Testing

Enter choice: 2
Enter Student's Name to remove: Arnold
Verbal Score: 77
Quantitative Score: 88
State: VA
remove(Arnold, 77, 88, VA) returns true

Choose an operation:
1: contains (string)
2: remove (string)
3: add (string)
4: print (traversal order)
9: stop Testing

Enter choice: 4
Choose a traversal order:
1: Preorder
2: Inorder
3: Postorder
3
The tree in Postorder is:
Brown in NJ earns 89 verbal, and 67 quantitative.
Thompson in NY earns 99 verbal, and 99 quantitative.
John in VA earns 89 verbal, and 89 quantitative.
Conner in NY earns 98 verbal, and 100 quantitative.
Smith in MD earns 89 verbal, and 89 quantitative.

Choose an operation:
1: contains (string)
2: remove (string)
3: add (string)
4: print (traversal order)
9: stop Testing

Enter choice: 3
Enter Student's Name to add: Arnold
Verbal Score: 77
Quantitative Score: 78
State: CT

Choose an operation:
1: contains (string)
2: remove (string)
3: add (string)
4: print (traversal order)
9: stop Testing

Enter choice: 4
Choose a traversal order:
1: Preorder
2: Inorder
3: Postorder
2
The tree in Inorder is:
Arnold in CT earns 77 verbal, and 78 quantitative.
Brown in NJ earns 89 verbal, and 67 quantitative.
John in VA earns 89 verbal, and 89 quantitative.
Thompson in NY earns 99 verbal, and 99 quantitative.
Smith in MD earns 89 verbal, and 89 quantitative.
Conner in NY earns 98 verbal, and 100 quantitative.

Choose an operation:
1: contains (string)
2: remove (string)
3: add (string)
4: print (traversal order)
9: stop Testing

Enter choice: 9

C:JavaBinSearchTree>

Now I just need the following missing code to test this system, and to make this all work:

import java.util.*;
import java.util.Scanner;
import java.io.BufferedReader;
import java.io.FileReader;
import java.io.File;
import java.io.IOException;

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

....

}

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