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AVLtree.java
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AVLtree.java
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package ss;
import java.util.Arrays;
import java.util.Collections;
import java.util.LinkedList;
public class AVLtree<T extends Comparable<? super T>> implements Tree<T> {
@Override
public void insert(T x){
root=insert(root,x);
}
@Override
public void remove(T x){
root=remove(root,x);
}
@Override
public void print(){
print(root);
}
public AVLtree(){
root=null;
}
private static class Node<U>{
public Node<U> left;
public Node<U> right;
public U item;
public int height;
public Node(U item){
this.left=null;
this.right=null;
height=0;
this.item=item;
}
}
private Node<T> root;
private Node<T> insert(Node<T> node, T x) {
if(node==null)
return new Node<>(x);
int compareresult=x.compareTo(node.item);
if(compareresult>0)
node.right=insert(node.right,x);
else if(compareresult<0)
node.left=insert(node.left,x);
else
System.out.println("重复"+node.item);
return balance(node);
}
private Node<T> remove(Node<T> node, T x) {
if(node==null)
return null;
int compareresult=x.compareTo(node.item);
if(compareresult>0)
node.right=remove(node.right,x);
else if(compareresult<0)
node.left=remove(node.left,x);
else
{
if(node.left!=null&&node.right!=null) {
T min = findmin(node.right);
node.item=min;
node.right=remove(node.right,min);
}
else{
node=node.left==null?node.right:node.left;
}
}
return balance(node);
}
private Node<T> balance(Node<T> node) {
if(node==null)
return null;
if(height(node.left)-height(node.right)>1)
//等于可以把相等高度作为单旋转
if(height(node.left.left)>=height(node.left.right))
node=rotatewithleft(node);
else
node=doublerotatewithleft(node);
else if(height(node.right)-height(node.left)>1)
if(height(node.right.right)>=height(node.right.left))
node=rotatewithright(node);
else
node=doublerotatewithright(node);
//下面重新计算高度是因为此时高度相差不超过1,未经过旋转平衡
//此处可能代码简洁性反而影响了清晰性
int leftheight=height(node.left);
int rightheight=height(node.right);
node.height=leftheight>rightheight?leftheight+1:
rightheight+1;
return node;
}
private Node<T> doublerotatewithleft(Node<T> node) {
node.left=rotatewithright(node.left);
return rotatewithleft(node);
}
private Node<T> rotatewithleft(Node<T> node) {
Node<T> tem=node.left;
node.left=tem.right;
tem.right=node;
node.height=max(height(node.left),height(node.right))+1;
tem.height=max(height(tem.left),height(tem.right))+1;
return tem;
}
private Node<T> doublerotatewithright(Node<T> node) {
node.right=rotatewithleft(node.right);
return rotatewithright(node);
}
private Node<T> rotatewithright(Node<T> node) {
Node<T> tem=node.right;
node.right=tem.left;
tem.left=node;
node.height=max(height(node.left),height(node.right))+1;
tem.height=max(height(tem.left),height(tem.right))+1;
return tem;
}
private int max(int a,int b){
return a>b?a:b;
}
private void print(Node<T> node) {
if(node!=null){
print(node.left);
System.out.print(node.item+" ");
print(node.right);
}
}
private int height(Node<T> node){
if(node!=null)
return node.height;
return -1;
}
private T findmin(Node<T> node){
if(node==null)
return null;
while (node.left!=null)
node=node.left;
return node.item;
}
public void printree(){
printree(new LinkedList<>(Arrays.asList(root)),new LinkedList<>());
}
//尽量按照树形打印
private void printree(LinkedList<Node<T>> q1,LinkedList<Node<T>> q2){
if(!q1.isEmpty()){
Node<T> tem;
while (!q1.isEmpty()){
tem=q1.poll();
System.out.print(tem.item+"("+tem.height+")"+" ");
if(tem.left!=null)
q2.add(tem.left);
if (tem.right!=null)
q2.add(tem.right);
}
System.out.println("");
printree(q2,q1);
}
}
public static void main(String[] s){
//Binarytree<String> tree=new Binarytree<>();
AVLtree<Integer> tree=new AVLtree<>();
String[] strings={"sd","sda","ddss"};
Integer[] ints={1,5,65,65,88,45,2,3,89,46,2,34,74,5,6};
foreach(tree, ints);
tree.print();
tree.printree();
// for(Integer x:new LinkedList<Integer>(Arrays.asList(ints)))
// System.out.print(x+" ");
tree.remove(2);
tree.print();
tree.printree();
}
public static <TT extends Comparable<? super TT>> void foreach(AVLtree<TT> tree, TT[] arrys) {
for(TT ss: arrys)
tree.insert(ss);
}
}