java 二叉查找树
//接口+抽象类+实现类
package wangChaoPA实习工作练习.com.进阶篇.二叉查找树;
import java.util.Iterator;
public interface Tree<E extends Comparable<E>>
{
// 从树中删除e
boolean delete(E e);
// 树的大小
int getSize();
// 中序遍历树
void inorder();
// 把e插入到tree中
boolean insert(E e);
// 树是否为空
boolean isEmpty();
/*
* 返回迭代器
*/
Iterator iterator();
// 后续遍历树
void postorder();
// 先序遍历树
void preorder();
// 查找e是否在tree中
boolean search(E e);
}
package wangChaoPA实习工作练习.com.进阶篇.二叉查找树;
import java.util.Iterator;
public abstract class AbstractTree<E extends Comparable<E>> implements Tree<E>
{
@Override
public boolean isEmpty()
{
return getSize() == 0;
}
@Override
public Iterator iterator()
{
return null;
}
}
package wangChaoPA实习工作练习.com.进阶篇.二叉查找树;
import java.util.ArrayList;
import java.util.Iterator;
public class BinaryTree<E extends Comparable<E>> extends AbstractTree<E>
{
class InorderItertor implements Iterator
{
private int current = 0;
private ArrayList<E> list = new ArrayList<E>();
public InorderItertor()
{
inorder(root);
}
@Override
public boolean hasNext()
{
if (this.current < this.list.size())
{
return true;
}
return false;
}
private void inorder(TreeNode<E> root)
{
if (root == null)
{
return;
}
inorder(root.left);
this.list.add(root.element);
inorder(root.right);
}
@Override
public Object next()
{
return this.list.get(this.current++);
}
// 删除当前元素 并刷新list
@Override
public void remove()
{
delete(this.list.get(this.current));// 删除当前元素
this.list.clear();// 清空list
inorder(root);// 重新排序
}
}
public static class TreeNode<E extends Comparable<E>>
{
E element;
TreeNode<E> left;
TreeNode<E> right;
public TreeNode(E e)
{
this.element = e;
}
}
protected TreeNode<E> root;
protected int size = 0;
public BinaryTree()
{
}
public BinaryTree(E[] objects)
{
for (int i = 0; i < objects.length; i++)
{
insert(objects[i]);
}
}
// 清空
public void clear()
{
this.root = null;
this.size = 0;
}
// 创建新的结点
protected TreeNode<E> creatNewNode(E e)
{
return new TreeNode<E>(e);
}
// 删除结点e 难点
@Override
public boolean delete(E e)
{
TreeNode<E> parent = null;
TreeNode<E> current = root;
// 找到需要删除的结点current以及它的父结点parent
while (current != null)
{
if (e.compareTo(current.element) < 0)
{
parent = current;
current = current.left;
}
else if (e.compareTo(current.element) > 0)
{
parent = current;
current = current.right;
}
else
{
break;
}
}
// e结点不在tree中
if (current == null)
{
return false;
}
// e在tree中 current结点没有左孩子
if (current.left == null)
{
// 删除的是根结点
if (parent == null)
{
// root指向current的右结点
this.root = current.right;
}
else
{// 不是根结点
if (e.compareTo(parent.element) < 0)
{
parent.left = current.right;// 父结点与current的右结点联系到一起
}
else
{
parent.right = current.right;
}
}
}
else
{// current结点有左孩子
// rightMost的父结点
TreeNode<E> parentOfRightMost = current;
// 左子树最右端的结点
TreeNode<E> rightMost = current.left;
while (rightMost.right != null)
{
parentOfRightMost = rightMost;
rightMost = rightMost.right;
}
// 替换值
current.element = rightMost.element;
if (parentOfRightMost.right == rightMost)
{
parentOfRightMost.right = rightMost.left;
}
else
{
parentOfRightMost.left = rightMost.left;
}
}
this.size--;
return true;
}
@Override
public int getSize()
{
return this.size;
}
// 中序遍历
@Override
public void inorder()
{
inorder(this.root);
}
protected void inorder(TreeNode<E> e)
{
if (this.root == null)
{
return;
}
inorder(this.root.left);
System.out.println(this.root.element + " ");
inorder(this.root.right);
}
public Iterator inorderIterator()
{
return new InorderItertor();
}
// 插入
@Override
public boolean insert(E e)
{
if (this.root == null)
{
this.root = creatNewNode(e);
}
else
{
// 父结点
TreeNode<E> parent = null;
// 当前结点
TreeNode<E> current = root;
// 找到需要插入的结点的父结点位置
while (current != null)
{
if (e.compareTo(current.element) < 0)
{
parent = current;
current = current.left;
}
else if (e.compareTo(current.element) > 0)
{
parent = current;
current = current.right;
}
else
{
return false;
}
}
// 插入
if (e.compareTo(parent.element) < 0)
{
parent.left = creatNewNode(e);
}
else
{
parent.right = creatNewNode(e);
}
}
this.size++;
return true;
}
// 返回从根结点到指定结点之间的结点
public ArrayList<TreeNode<E>> path(E e)
{
ArrayList<TreeNode<E>> list = new ArrayList<TreeNode<E>>();
TreeNode<E> current = this.root;
while (current != null)
{
list.add(current);
if (e.compareTo(current.element) < 0)
{
current = current.left;
}
else if (e.compareTo(current.element) > 0)
{
current = current.right;
}
else
{
break;
}
}
return list;
}
// 后序遍历
@Override
public void postorder()
{
postorder(this.root);
}
protected void postorder(TreeNode<E> e)
{
if (this.root == null)
{
return;
}
inorder(this.root.left);
inorder(this.root.right);
System.out.println(this.root.element + " ");
}
// 先序遍历
@Override
public void preorder()
{
preorder(this.root);
}
protected void preorder(TreeNode<E> e)
{
if (this.root == null)
{
return;
}
System.out.println(this.root.element + " ");
inorder(this.root.left);
inorder(this.root.right);
}
@Override
public boolean search(E e)
{
TreeNode<E> current = this.root;
while (current != null)
{
if (e.compareTo(current.element) < 0)
{
current = current.left;
}
else if (e.compareTo(current.element) > 0)
{
current = current.left;
}
else
{
return true;
}
}
return false;
}
}
