Binary Search Tree Assignment
Overview
For this assignment you will be implementing the Binary Search Tree ADT and a number of associated functions. It would be very helpful to read chapters 9 and 10 in the Java Software Structures book.
Table of Contents
Files to complete
Support Code API
Part One: Clone, Branch, and Import Project
Part Two: Implement the BinaryTreeNode Interface
Part Three: Implement the BinaryTreeUtility Interface
Part Four: Implement the BinarySearchTree Interface
Part Five: Commit Project and Submit Pull Request
Book
This assignment is based off Chapter 9 and Chapter 10 in Java Software Structures
Files to complete
You are expected to write an implementation for each of the interfaces listed in the classes presented in the config package provided. As with the last assignment, you must specify which implementation you would like us to grade in this file.
Test files
In the test folder, you are provided with several JUnit test cases that will help you keep on track while completing this assignment. I recommend you run the tests often and use them as a checklist of things to do next. You are not allowed to modify my test cases, but you will need to add your own to fill out the test suite. If you have errors in these files, it means the structure of the files found in the src folder have been altered in a way that will cause your submission to lose points.
Support Code API
The Support Code’s comments have been generated into a nicely formatted API that can be found here:
https://jd12.github.io/binary-search-tree/
It is highly recommended that you spend some time simply reading over the comments in each of the interfaces and classes provided.
Part One: Clone, Branch, and Import Project
Begin by cloning the provided project, creating your dev branch, and importing it into your workspace.
git clone <url for github repository>
After cloning this repository you want to run these commands
cp pre-commit .git/hooks
chmod +x .git/hooks/pre-commit
Then you want to create a development branch
git branch development
git checkout development
You should then import it to your IDE of choice.
By default, your project should have no errors and contain the following root items:
src - The source folder where all code you are submitting must go. You can change anything you want in this folder, you can add new files, etc...
test - The test folder where all of the public unit tests are available
support - This folder contains support code that I encourage you to use (and must be used to pass certain tests). I would be very careful changing files in this folder.
JUnit 4 - A library that is used to run the test programs
JRE System Library - This is what allows java to run
If you are missing any of the above or errors are present in the project, seek help immediately so you can get started on the project right away.
Part Two: Implement the BinaryTreeNode Interface
A BinaryTreeNode represents a node in a binary tree. It stores data of generic type T and may have a right and a left child, each a reference to another BinaryTreeNode. The BinaryTreeNode interface includes standard getters and setters for a BinaryTreeNode’s right and left children as well as its data.
Part Three: Implement the BinaryTreeUtility Interface
The BinaryTreeUtility interface provides basic functions for working with a binary tree.
Depth -- The depth of the tree is the maximum level of any leaf node in the tree. Recall that the level of a node begins at zero for the root of a tree with no children. A child of the root is at level 1.
Balance -- The balance of a tree measures how close it is to a full or complete tree. You will implement the method isBalanced(BinaryTreeNode<T> root, int tolerance) which determines whether the maximum difference in the depth of any two children is no larger than the given tolerance value.
Testing the BST property -- Recall that a BST is a binary tree that also satisfies a special sorting property: if all elements in left subtree of any node X are less than or equal to node X and all nodes in the right subtree of X are greater than X. You will write a function isBST(root) which returns true if root is the root of a valid binary search tree. Your function need not explicitly test basic requirements of the binary tree (e.g. that there is a unique path from the root to every node in the tree). Testing the BST property has a nice recursive solution, but it requires some thought. If you’d like a hint, please see the following wikipedia page:
http://en.wikipedia.org/wiki/Binary_search_tree#Determining_whether_a_tree_is_a_BST_or_not
Iterators -- You will also provide three methods getPreOrderIterator(BinaryTreeNode<T> root), getInOrderIterator(BinaryTreeNode<T> root), getPostOrderIterator(BinaryTreeNode<T> root) each returning an iterator that follows the stated traversal over a binary tree.
Hint: A PreOrderIterator class has been provided as an example to get started. Tip: The iterative versions of Post / In order traversal can be found here: http://en.wikipedia.org/wiki/Tree_traversal
Feeling ambitious?
See if you can make a Level-Order iterator. http://en.wikipedia.org/wiki/File:Sorted_binary_tree_breadth-first_traversal.svg
Part Four: Implement the BinarySearchTree Interface
Next you will implement methods underlying the BST structure.
Transformers -- Add and remove are the main transformers of a BST. These must add or remove elements while maintaining the BST property. You may follow the textbook’s implementation of these methods. You may also find variations of the methods that work.
Observers -- You will implement an isEmpty() method and a size() method. In addition, you will implement the getMinimum() and getMaximum() functions, which return the smallest and largest values stored in the BST.
Iterator -- This function returns an iterator that supports in-order access to the nodes of the BST. Recall that an in-order traversal of a BST results in a sorted order due to the BST property.
Bonus: The method returning an iterator should complete in O(1) time, so it should not compute the entire sequential order ahead of time
If you choose to implement an iterator method that returns in O(1) time, you will receive extra credit. This means you should not compute the traversal in its entirety when creating and returning the iterator. Instead, the iterator should be initialized and returned as a result of the function call, with the next element in the traversal computed with each call to next().
Part Five: Commit Project and Submit Pull Request
When you have finished your solution and are ready to submit, make your final commit and push everything up to Github. Submit a pull request to the main repository. Mark jd12 as a reviewer so that I know your code is ready to be reviewed.