java数据结构——AvlTree（平衡二叉查找树）

package com.tig.tree;

/**
* 3, 2, 1, 4, 5, 6, 7, 10, 9, 8
* Created by Tig on 2017/5/19.
*/
public class AvlTree<E extends Comparable<? super E>> {

private AvlNode<E> root;

public AvlTree() {
root = null;
}

public void insert(E x) {
root = insert(x, root);
}

private AvlNode<E> insert(E x, AvlNode<E> t) {

if (t == null) {
return new AvlNode<>(x, null, null);
}

int compareResult = x.compareTo(t.element);

if (compareResult < 0) {

t.left = insert(x, t.left);
if (height(t.left) - height(t.right) == 2) {

if (x.compareTo(t.left.element) < 0) {
t = rotateWithLeftChild(t);
} else {
t = doubleWithLeftChild(t);
}
}
} else if (compareResult > 0) {

t.right = insert(x, t.right);

if (height(t.right) - height(t.left) == 2) {

if (x.compareTo(t.right.element) > 0) {
t = rotateWithRightChild(t);
} else {
t = doubleWithRightChild(t);
}
}
}

t.hight = Math.max(height(t.left), height(t.right)) + 1;

return t;
}

/**
*          ③
*         /
*        ②
*       /
*      ①
* @param k2
* @return
*/
private AvlNode<E> rotateWithLeftChild(AvlNode<E> k2) {
AvlNode<E> k1 = k2.left;
k2.left = k1.right;
k1.right = k2;
k2.hight = Math.max(height(k2.left), height(k2.right)) + 1;
k1.hight = Math.max(height(k1.left), k2.hight ) + 1;
return k1;
}

private AvlNode<E> doubleWithLeftChild(AvlNode<E> k3) {
k3.left = rotateWithRightChild(k3.left);
return rotateWithLeftChild(k3);
}

/**
*     ③
*      \
*       ④
*        \
*         ⑤
* @param k1
* @return
*/
private AvlNode<E> rotateWithRightChild(AvlNode<E> k1) {
AvlNode<E> k2 = k1.right;
k1.right = k2.left;
k2.left = k1;
k1.hight = Math.max(height(k1.left), height(k1.right)) + 1;
k2.hight = Math.max(height(k2.right), k1.hight ) + 1;
return k2;
}

/**
*     ⑦
*      \
*       ⑩
*      /
*     ⑨
* @param k1
* @return
*/
private AvlNode<E> doubleWithRightChild(AvlNode<E> k1) {
k1.right = rotateWithLeftChild(k1.right);
return rotateWithRightChild(k1);
}

public int height(AvlNode<E> t){
return t == null ? -1 : t.hight;
}

public static class AvlNode<E> {

E element;      //the date in the node

AvlNode<E> left;    //Left child

AvlNode<E> right;   //right child

int hight;  //Height

public AvlNode() {
}

public AvlNode(E element) {
this(element, null, null);
}

public AvlNode(E element, AvlNode<E> left, AvlNode<E> right) {
this.element = element;
this.left = left;
this.right = right;
this.hight = 0;
}
}

public static void main(String[] args) {

AvlTree<Integer> avlTree = new AvlTree<>();

avlTree.insert(3);
avlTree.insert(2);
avlTree.insert(1);
avlTree.insert(4);
avlTree.insert(5);
avlTree.insert(6);
avlTree.insert(7);
avlTree.insert(10);
avlTree.insert(9);
avlTree.insert(8);
}
}