JAVA程序语言调试、代写JAVA程序代写、program编程代做

日期：2021-04-27 10:52

Introduction

The objective from this assignment it to gain experience with binary tree

traversals, and also implementing and testing the validity of AVL trees.

To help start with the assignment, you are provided with the file Assignment1-

Source.zip (see BrightSpace). This file contains both the source code and the

documentation (i.e., JAVADOC).

Tasks

The main tasks for this assignment are:

? Implemented the Binary Tree Traversal methods

? Implement the core functionalities for an AVL Tree

? Test if your AVL implementation is correct

? Improve the efficiency of your AVL implementation

1. Implementing Binary Tree Traversal Methods

The source code contains a partial implementation of Binary Tree Traversals

in a file called Traversal.java in the dsa.impl package. Your work in this section

must be in this class.

You must implement the following methods:

? private void visitNode( BTNode<T> x ) – print the element in the node x.

? public void preOrderTraversal( Object bt ) – preOrderTraversal of the tree

bt.

? public void preOrderTraversal( Object bt ) – inOrderTraversal of the tree

bt.

? public void postOrderTraversal( Object bt ) – postOrderTraversal of the

tree bt.

Note that before implementing the methods preOrderTraversal,

inOrderTraversal and postOrderTraversal, you need to replace the type

Object with the most suitable type for the parameter bt.

You are also required to indicate in comment the reason for your choice:

? ITree<T>

? AbstractBinaryTree<T>

? ProperLinkedBinaryTree

? BinarySearchTree

? AVL

2. Implementing AVL Tree Methods

The source code contains a partial implementation of an AVL Tree in a file

called AVLTree.java in the dsa.impl package. Your work in this section must be

in this class.

You must implement the following methods:

? private void rotate( INode<T> x ) – trinode restructuring (the three nodes

are: x, its parent and its grandparent).

Hint: You can cast to an INode<T> to a BTNode in the same way as you

did in Worksheet 4.

? public void insert( T element ) – insert a value into the AVL tree.

? public void remove( T element) – remove a value from the AVL tree.

? public boolean contains(T value) – check to see if a value is contained in

the AVL tree. Returns true if the value is in the tree, or false if not.

If you wish, you may create other methods that help you to complete the task

(e.g. rightRotate(INode<T> n), leftRotate(INode<T> n), etc.).

3. Testing Your AVL Implementation

It is important to check whether your implementations are correct. A good way

to do this is to use your tree to perform some operations, and then check if the

outcome is correct. This is best done using a program, rather than doing it

manually every time.

In the Main class, write code that will automatically perform some operations

on your tree implementations, to check if they are correct. Here are some

suggestions:

- A simple test: perform some operations on the trees, then print the tree

using you previously implemented Binary Tree Traversal methods

and manually compare it to what you expect the output to be. You need

to use as many traversal methods as needed to capture the structure

of the tree.

- A more complex test: A Binary Search Tree (BST) implementation has

been provided. Write a method to compare the structure and contents

of your AVL with a BST that represents the correct output.

- More complex again: Create text files that represent operations to be

performed on different types of trees (e.g. Insert 10 to insert 10 into the

tree, Remove 25 to remove 25, etc.). Write code to read these files

and perform the operations on the trees, then compare the outputs.

In all of the above cases, you need to know what the correct output of your

implementation should be. The operations you perform should test all the

different types of rotations that are possible (they should cause LL, RR, LR

and RL rotations, and both at the root and deeper in the tree).

4. Improving Efficiency of Your AVL Implementation

In this implementation, the height of each node must be recalculated every

time it is needed, which in practice makes both the insert(…) and remove(…)

methods O(n) operations, where n is the number of nodes in the tree.

Adjust the implementation of the AVL tree so that each node stores its own

height, and these are updated only when necessary (Hint: updating the

heights of nodes should be no worse than O(h) complexity following an

insert(…) or remove(…) operation, where h is the height of the tree).

For this task, you must not change the public API of the AVLTree class. All

your code must be inside the AVLTree.java file.

Submission

This is an individual assignment. Therefore all work submitted must

be your own. Refer to the UCD Plagiarism Policy for more

(http://www.ucd.ie/t4cms/RevisedPlagiarismProtocol.pdf).

? All code should be well-formatted and well-commented to describe

what it is trying to do.

? If you write code outside the Main.java, Traversal.java and AVLTree.java

files, it will not be noticed when grading. Write code only in these files.

? Submit a single .zip file to BrightSpace.

o This should include only the ‘src’ folder from your project that

contains all your code.