package com.test.tree; import java.util.Iterator; /**
* 编写TreeSet类的实现程序，其中相关的迭代器使用二叉查找树。
* 在每个节点上添加一个指向其父节点的链
* @author wyl
* @param <T>
*/
public class MyTreeSet<T extends Comparable<? super T>> { private BinaryNode<T> root; //根节点
int modCount = 0; //记录调整树结构的次数 public MyTreeSet(){
root = null;
}
/**
* 定义二叉查找树的节点
*/
private class BinaryNode<T>{
T data; //节点的值
BinaryNode<T> left; //节点的左节点
BinaryNode<T> right; //节点右节点
BinaryNode<T> parent; //节点的父节点 public BinaryNode(T data){
this(data, null, null, null);
} public BinaryNode(T data, BinaryNode<T> lt, BinaryNode<T> rt, BinaryNode<T> pt) {
this.data = data;
this.left = lt;
this.right = rt;
this.parent = pt;
}
} /**
* 定义TreeSet的迭代器
* @return
*/
public Iterator iterator(){
return new MyTreeSetIterator();
} private class MyTreeSetIterator implements Iterator { private BinaryNode<T> current = findMin(root);
private BinaryNode<T> previous;
private int expectedModCount = modCount;
private boolean okToRemove = false;
private boolean atEnd = false;
@Override
public boolean hasNext() {
// TODO Auto-generated method stub
return !atEnd;
} @Override
public T next() {
// TODO Auto-generated method stub
if(modCount != expectedModCount){
try {
throw new CurrentModificationException();
} catch (CurrentModificationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(!hasNext()){
try {
throw new NoSuchElementException();
} catch (NoSuchElementException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} T nextItem = current.data;
previous = current;
if(current.right != null){
current = findMin(current.right);
}else{
BinaryNode<T> child = current;
current = current.parent;
while(current != null && current.left != child){
child = current;
current = current.parent;
}
if(current == null){
atEnd = true;
}
}
okToRemove = true;
return nextItem;
} @Override
public void remove(){
// TODO Auto-generated method stub
if(modCount != expectedModCount){
try {
throw new CurrentModificationException();
} catch (CurrentModificationException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if(!okToRemove){
throw new IllegalStateException();
} try {
MyTreeSet.this.remove(previous.data);
} catch (UnderflowException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
okToRemove = false;
}
} public void makeEmpty(){
modCount++ ;
root = null;
} public boolean isEmpty(){
return root == null;
}
public boolean contains(T x){
return contains(x, root);
} public boolean contains(T x, BinaryNode<T> t){
if(t == null){
return false;
}
int compareResult = x.compareTo(t.data);
if(compareResult < 0){
return contains(x, t.left);
}else if(compareResult > 0){
return contains(x, t.right);
}else{
return true;
}
} public T findMin(){
if(isEmpty()){
try {
throw new UnderflowException();
} catch (UnderflowException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return findMin(root).data;
} public T findMax(){
if(isEmpty()){
try {
throw new UnderflowException();
} catch (UnderflowException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
return findMax(root).data;
} public void insert(T x){
root = insert(x, root, null);
} public void remove(T x) throws UnderflowException{
root = remove(x, root);
} public void printTree(){
if(isEmpty()){
System.out.println("Empty tree");
}else{
printTree(root);
}
} public void printTree(BinaryNode<T> t){
if(t != null){
printTree(t.left);
System.out.println(t.data);
printTree(t.right);
}
} public BinaryNode<T> remove(T x, BinaryNode<T> t){
if(t == null){
try {
throw new UnderflowException();
} catch (UnderflowException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
int compareResult = x.compareTo(t.data);
if(compareResult < 0){
t = remove(x, t.left);
}else if(compareResult > 0){
t = remove(x, t.right);
}else if(t.left != null && t.right != null){
//要删除的节点是含有左右子树的节点
t.data = findMin(t.right).data;//将右子树的最小值作为根节点
t.right = remove(t.data, t.right);
}else{
modCount++ ;
BinaryNode<T> oneChild;
oneChild = (t.left == null)?t.left:t.right;
oneChild.parent = t.parent;
t = oneChild;
}
return t;
} public BinaryNode<T> insert(T x, BinaryNode<T> t, BinaryNode<T> parent){
if(t == null){
modCount++ ;
//空树
return new BinaryNode(x, null, null, parent);
}
int compareResult = x.compareTo(t.data);
if(compareResult < 0){
//要插入的数小于节点值，插入到左子树
t.left = insert(x, t.left, t);
}else if(compareResult > 0){
//要插入的数小于节点值，插入到左子树
t.right = insert(x, t.right, t);
}else{ }
return t;
} public BinaryNode<T> findMin(BinaryNode<T> t){
// TODO Auto-generated method stub
if(t == null){
try {
throw new UnderflowException();
} catch (UnderflowException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else if(t.left == null){
return t;
}
return findMin(t.left);
} public BinaryNode<T> findMax(BinaryNode<T> t){
// TODO Auto-generated method stub
if(t == null){
try {
throw new UnderflowException();
} catch (UnderflowException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}else if(t.right == null){
return t;
}
return findMax(t.right);
} public static void main(String[] args) {
MyTreeSet<Integer> myTreeSet = new MyTreeSet<Integer>();
myTreeSet.insert(24);
myTreeSet.insert(23);
myTreeSet.insert(16);
myTreeSet.insert(20);
myTreeSet.insert(28);
myTreeSet.insert(29);
System.out.println("最小值： "+ myTreeSet.findMin());
System.out.println("最大值： "+ myTreeSet.findMax());
Iterator iter = myTreeSet.iterator();
while(iter.hasNext()){
System.out.print(iter.next() + "、");
} }
}
class UnderflowException extends Exception{}
class CurrentModificationException extends Exception{}
class NoSuchElementException extends Exception{}