avl树的插入（含单旋转，双旋转）

学习中写的，所以注释少，结构杂乱，难免有不足之处，望批评改正。如有需要笔者解释的地方，请将问题发到笔者邮箱(lixding@163.com)。

public class AVLTreeClass <AnyType extends Comparable<AnyType>>{

//节点类

public static class AVLNode<AnyType>{

AnyType data;//数据

AVLNode<AnyType> leftNode;//左子树

AVLNode<AnyType> rightNode;//右子树

int height=0;//高度

public AVLNode(AnyType data){

this.data=data;

this.leftNode=null;

this.rightNode=null;

}

public AVLNode(AVLNode<AnyType> left,AVLNode<AnyType> right,AnyType data){

this.data=data;

this.leftNode=left;

this.rightNode=right;

}

public AVLNode() {}

//获取树的高度

public int getHeight(AVLNode<AnyType> node){

return node==null?-1:node.height;//空树返回-1

}

}

private AVLNode<AnyType> root=null;//定义根节点

public AVLTreeClass(){

}

public void insert(AnyType x){

root=insert(x,root);

}

public AnyType getRoot(){

return root.data;

}

private AVLNode<AnyType> insert(AnyType x,AVLNode<AnyType> node){

if(node==null){

return new AVLNode<AnyType>(x);

}

int compareConsult=x.compareTo(node.data);

if(compareConsult<0){

node.leftNode=insert(x,node.leftNode);

if(node.getHeight(node.leftNode)-node.getHeight(node.rightNode)==2){

if(x.compareTo(node.data)<0) {

node=rotateWithLeftChild(node);

}

else{

node=doubleWithLeftChild(node);

}

}

}

else if(compareConsult>0){

node.rightNode=insert(x,node.rightNode);

if(node.getHeight(node.rightNode)-node.getHeight(node.leftNode)==2){

if(x.compareTo(node.data)>0) {

node=rotateWithRightChild(node);

}

else{

node=doubleWithRightChild(node);

}

}

}

else

;//do nothing

node.height=Math.max(node.getHeight(node.leftNode), node.getHeight(node.rightNode))+1;

return node;

}

private AVLNode<AnyType> doubleWithRightChild(AVLNode<AnyType> node) {

node.rightNode=rotateWithLeftChild(node.rightNode);

return rotateWithRightChild(node);

}

private AVLNode<AnyType> doubleWithLeftChild(AVLNode<AnyType> node) {

node.leftNode=rotateWithRightChild(node.leftNode);

return rotateWithLeftChild(node);

}

private AVLNode<AnyType> rotateWithRightChild(AVLNode<AnyType> node) {

AVLNode<AnyType> node2=node.rightNode;

node.rightNode=node2.leftNode;

node2.leftNode=node;

node.height=Math.max(node.getHeight(node.leftNode), node.getHeight(node.rightNode))+1;

node2.height=Math.max(node2.getHeight(node2.leftNode),node.height)+1;

return node2;

}

private AVLNode<AnyType> rotateWithLeftChild(AVLNode<AnyType> node) {

AVLNode<AnyType> node2=node.leftNode;

node.leftNode=node2.rightNode;

node2.rightNode=node;

node.height=Math.max(node.getHeight(node.leftNode), node.getHeight(node.rightNode))+1;

node2.height=Math.max(node2.getHeight(node2.leftNode), node.height)+1;

return node2;

}

}