示例
平衡搜索树示例
AVL.java源代码
package com.reign.gcld.chapter12;
/**
* AVL树是一棵自平衡二叉搜索树，
* 其中，每个节点的左右子树高度差不超过1
*/
public class AVL extends BST {
public static void main(String[] args) {
AVL tree = new AVL();
//插入测试
Entry entryG = new Entry("G","G");
tree.insert(entryG);
Entry entryE = new Entry("E","E");
tree.insert(entryE);
Entry entryR = new Entry("R","R");
tree.insert(entryR);
Entry entryB = new Entry("B","B");
tree.insert(entryB);
Entry entryN = new Entry("N","N");
tree.insert(entryN);
Entry entryY = new Entry("Y","Y");
tree.insert(entryY);
Entry entryK = new Entry("K", "K");
tree.insert(entryK);
//中序遍历
Iterable nodes = tree.inOrder(tree.root);
for (Node node : nodes) {
System.out.println(node + "#balFac=" + tree.getBalFac(node));
}
// Entry entryM = new Entry("M", "M");
// tree.insert(entryM);
// //中序遍历
// Iterable nodes1 = tree.inOrder(tree.root);
// for (Node node : nodes1) {
// System.out.println(node+"#balFac="+tree.getBalFac(node));
// }
tree.delete(entryY);
//中序遍历
Iterable nodes2 = tree.inOrder(tree.root);
for (Node node : nodes2) {
System.out.println(node + "#balFac=" + tree.getBalFac(node));
}
}
@Override
public void delete(Entry e) {
Node x = search(e);
if (x == null) {
return ;
}
super.delete(x);
for (Node z=super.hot; z != null; z=z.getParent()) {
if (!avlBalanced(z)) {
Node g = z;
Node p = getTallerChild(g);
Node v = getTallerChild(p);
if (super.isLChild(p)) {
if (super.isLChild(v)) {
//left-left:一次右旋
p.setParent(g.getParent());
z = rightRotate(v, g, p, v.getLeft(), v.getRight(), p.getRight(), g.getRight());
} else {
//left_right:先左旋再右旋
v.setParent(g.getParent());
z = leftRightRotate(p, v, g, p.getLeft(), v.getLeft(), v.getRight(), g.getRight());
}
} else {
if (super.isRChild(v)) {
//right-right:一次左旋
p.setParent(g.getParent());
z = leftRotate(g, p, v, g.getLeft(), p.getLeft(), v.getLeft(), v.getRight());
} else {
//right-left:先右旋，再左旋
v.setParent(g.getParent());
z = rightLeftRotate(g, v, g, g.getLeft(), v.getLeft(), v.getRight(), p.getRight());
}
}
}
super.updateHeight(z);
}
return ;
}
@Override
public Node insert(Entry e) {
Node w = super.insert(e);
for (Node z=super.hot; z != null; z=z.getParent()) {
if (!avlBalanced(z)) {
Node g = z;
Node p = getTallerChild(g);
Node v = getTallerChild(p);
if (super.isLChild(p)) {
if (super.isLChild(v)) {
//left-left:一次右旋
p.setParent(g.getParent());
if (super.isLChild(g)) {
g.getParent().setLeft(p);
}else {
g.getParent().setRight(p);
}
z = rightRotate(v,g,p, v.getLeft(), v.getRight(), p.getRight(), g.getRight());
}else {
//left_right:先左旋再右旋
v.setParent(g.getParent());
if (super.isLChild(g)) {
g.getParent().setLeft(v);
}else {
g.getParent().setRight(v);
}
z = leftRightRotate(p, v, g, p.getLeft(), v.getLeft(), v.getRight(), g.getRight());
}
}else {
if (super.isRChild(v)) {
//right-right:一次左旋
p.setParent(g.getParent());
if (super.isLChild(g)) {
g.getParent().setLeft(p);
}else {
g.getParent().setRight(p);
}
z = leftRotate(g,p,v, g.getLeft(), p.getLeft(), v.getLeft(), v.getRight());
}else {
//right-left:先右旋，再左旋
v.setParent(g.getParent());
if (super.isLChild(g)) {
g.getParent().setLeft(v);
}else {
g.getParent().setRight(v);
}
z = rightLeftRotate(g, v, g, g.getLeft(), v.getLeft(), v.getRight(), p.getRight());
}
}
}
super.updateHeight(z);
}
return w;
}
private Node rightLeftRotate(Node x, Node y, Node z, Node T1, Node T2, Node T3, Node T4) {
x.setLeft(T1);
if (T1 != null) {
T1.setParent(x);
}
x.setRight(T2);
if (T2 != null) {
T2.setParent(x);
}
updateHeight(x);
z.setLeft(T3);
if (T3 != null) {
T3.setParent(z);
}
z.setRight(T4);
if (T4 != null) {
T4.setParent(z);
}
updateHeight(z);
y.setLeft(x);
x.setParent(y);
y.setRight(z);
z.setParent(y);
updateHeight(y);
return y;
}
private Node leftRotate(Node x, Node y, Node z, Node T1, Node T2, Node T3, Node T4) {
x.setLeft(T1);
if (T1 != null) {
T1.setParent(x);
}
x.setRight(T2);
if (T2 != null) {
T2.setParent(x);
}
updateHeight(x);
z.setLeft(T3);
if (T3 != null) {
T3.setParent(z);
}
z.setRight(T4);
if (T4 != null) {
T4.setParent(z);
}
updateHeight(z);
y.setLeft(x);
x.setParent(y);
y.setRight(z);
z.setParent(y);
updateHeight(y);
return y;
}
private Node leftRightRotate(Node x, Node y, Node z, Node T1, Node T2, Node T3, Node T4) {
x.setLeft(T1);
if (T1 != null) {
T1.setParent(x);
}
x.setRight(T2);
if (T2 != null) {
T2.setParent(x);
}
updateHeight(x);
z.setLeft(T3);
if (T3 != null) {
T3.setParent(z);
}
z.setRight(T4);
if (T4 != null) {
T4.setParent(z);
}
updateHeight(z);
y.setLeft(x);
x.setParent(y);
y.setRight(z);
z.setParent(y);
updateHeight(y);
return y;
}
private Node rightRotate(Node x, Node y, Node z, Node T1, Node T2, Node T3, Node T4) {
x.setLeft(T1);
if (T1 != null) {
T1.setParent(x);
}
x.setRight(T2);
if (T2 != null) {
T2.setParent(x);
}
updateHeight(x);
z.setLeft(T3);
if (T3 != null) {
T3.setParent(z);
}
z.setRight(T4);
if (T4 != null) {
T4.setParent(z);
}
updateHeight(z);
y.setLeft(x);
x.setParent(y);
y.setRight(z);
z.setParent(y);
updateHeight(y);
return y;
}
private Node getTallerChild(Node x) {
int h1 = super.getStature(x.getLeft());
int h2 = super.getStature(x.getRight());
if (h1 > h2) {
return x.getLeft();
}else if (h1 < h2) {
return x.getRight();
}else {
//等高时，选择与父亲同侧的
if (super.isLChild(x)) {
return x.getLeft();
}else {
return x.getRight();
}
}
}
private boolean avlBalanced(Node x) {
boolean result = false;
if (getBalFac(x) > -2 && getBalFac(x) < 2) {
result = true;
}
return result;
}
private int getBalFac(Node x) {
return getStature(x.getRight()) - getStature(x.getLeft());
}
}