Class BSTreeSetTester<K extends java.lang.Comparable<K>>

java.lang.Object

BSTreeSetTester<K>

All Implemented Interfaces:

java.lang.Iterable<K>, SetTesterADT<K>

public class BSTreeSetTester<K extends java.lang.Comparable<K>>
extends java.lang.Object
implements SetTesterADT<K>

SetTesterADT implementation using a Binary Search Tree (BST) as the data structure.

The BST rebalances if a specified threshold is exceeded (explained below). If rebalanceThreshold is non-positive (<=0) then the BST DOES NOT rebalance. It is a basic BStree. If the rebalanceThreshold is positive then the BST does rebalance. It is a BSTreeB where the last B means the tree is balanced.

Rebalancing is triggered if the absolute value of the balancedFfactor in any BSTNode is > to the rebalanceThreshold in its BSTreeSetTester. Rebalancing requires the BST to be completely rebuilt.

Author:

CS367

Field Summary

Fields

Modifier and Type	Field and Description
(package private) boolean	isBalanced True iff tree is balanced, i.e., if rebalanceThreshold is NOT exceeded by absolute value of balanceFactor in any of the tree's BSTnodes.Note if rebalanceThreshold is non-positive, isBalanced must be true.
(package private) int	numKeys Number of items in this tree
(package private) int	rebalanceThreshold rebalanceThreshold <= 0 DOES NOT REBALANCE (BSTree). rebalanceThreshold >0 rebalances the tree (BSTreeB).
(package private) BSTNode<K>	root Root of this tree

Constructor Summary

Constructors

Constructor and Description
BSTreeSetTester(int rbt) Constructs an empty BSTreeSetTester with a given rebalanceThreshold.

Method Summary

Modifier and Type	Method and Description
void	add(K key) Add node to binary search tree.
void	clear() Clears the tree, i.e., removes all the keys in the tree.
boolean	contains(K key) Returns true iff the key is in the binary search tree.
void	displayTree(int maxDisplayLevels) Displays the top maxNumLevels of the tree.
private void	displayTreeHelper(BSTNode<K> n, int curDepth, int maxDisplayLevels)
java.util.Iterator<K>	iterator() Return an iterator for the binary search tree.
void	rebalance() Rebalances the tree by: 1.
int	size() Returns the number of keys in the tree.
private BSTNode<K>	sortedArrayToBST(K[] keys, int start, int stop) Recursively rebuilds a binary search tree from a sorted array.
java.util.List<K>	subSet(K minValue, K maxValue) Returns the sorted list of keys in the tree that are in the specified range (inclusive of minValue, exclusive of maxValue).

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.lang.Iterable

forEach, spliterator

Field Detail

root

BSTNode<K extends java.lang.Comparable<K>> root

Root of this tree

numKeys

int numKeys

Number of items in this tree

rebalanceThreshold

int rebalanceThreshold

rebalanceThreshold <= 0 DOES NOT REBALANCE (BSTree).
rebalanceThreshold >0 rebalances the tree (BSTreeB).

isBalanced

boolean isBalanced

True iff tree is balanced, i.e., if rebalanceThreshold is NOT exceeded by absolute value of balanceFactor in any of the tree's BSTnodes.Note if rebalanceThreshold is non-positive, isBalanced must be true.

Constructor Detail

BSTreeSetTester

public BSTreeSetTester(int rbt)

Constructs an empty BSTreeSetTester with a given rebalanceThreshold.

Parameters:

rbt - the rebalance threshold

Method Detail

add

public void add(K key)

Add node to binary search tree. Remember to update the height and balancedFfactor of each node. Also rebalance as needed based on rebalanceThreshold.

Specified by:

add in interface SetTesterADT<K extends java.lang.Comparable<K>>

Parameters:

key - the key to add into the BST

Throws:

java.lang.IllegalArgumentException - if the key is null

DuplicateKeyException - if the key is a duplicate

rebalance

public void rebalance()

Rebalances the tree by: 1. Copying all keys in the BST in sorted order into an array. Hint: Use your BSTIterator. 2. Rebuilding the tree from the sorted array of keys.

sortedArrayToBST

private BSTNode<K> sortedArrayToBST(K[] keys,
                                    int start,
                                    int stop)

Recursively rebuilds a binary search tree from a sorted array. Reconstruct the tree in a way similar to how binary search would explore elements in the sorted array. The middle value in the sorted array will become the root, the middles of the two remaining halves become the left and right children of the root, and so on. This can be done recursively. Remember to update the height and balanceFactor of each node.

Parameters:

keys - the sorted array of keys

start - the first index of the part of the array used

stop - the last index of the part of the array used

Returns:

root of the new balanced binary search tree

contains

public boolean contains(K key)

Returns true iff the key is in the binary search tree.

Specified by:

contains in interface SetTesterADT<K extends java.lang.Comparable<K>>

Parameters:

key - the key to search

Returns:

true if the key is in the binary search tree

Throws:

java.lang.IllegalArgumentException - if key is null

subSet

public java.util.List<K> subSet(K minValue,
                                K maxValue)

Returns the sorted list of keys in the tree that are in the specified range (inclusive of minValue, exclusive of maxValue). This can be done recursively.

Specified by:

subSet in interface SetTesterADT<K extends java.lang.Comparable<K>>

Parameters:

minValue - the minimum value of the desired range (inclusive)

maxValue - the maximum value of the desired range (exclusive)

Returns:

the sorted list of keys in the specified range

Throws:

java.lang.IllegalArgumentException - if either minValue or maxValue is null, or minValue is larger than maxValue

iterator

public java.util.Iterator<K> iterator()

Return an iterator for the binary search tree.

Specified by:

iterator in interface java.lang.Iterable<K extends java.lang.Comparable<K>>

Specified by:

iterator in interface SetTesterADT<K extends java.lang.Comparable<K>>

Returns:

the iterator

clear

public void clear()

Clears the tree, i.e., removes all the keys in the tree.

Specified by:

clear in interface SetTesterADT<K extends java.lang.Comparable<K>>

size

public int size()

Returns the number of keys in the tree.

Specified by:

size in interface SetTesterADT<K extends java.lang.Comparable<K>>

Returns:

the number of keys

displayTree

public void displayTree(int maxDisplayLevels)

Displays the top maxNumLevels of the tree. DO NOT CHANGE IT!

Specified by:

displayTree in interface SetTesterADT<K extends java.lang.Comparable<K>>

Parameters:

maxDisplayLevels - from the top of the BST that will be displayed

displayTreeHelper

private void displayTreeHelper(BSTNode<K> n,
                               int curDepth,
                               int maxDisplayLevels)