[JavaSE] data structure (Basic AVL Tree concept), javaseavl

[JavaSE] data structure (Basic AVL Tree concept), javaseavl

The AVL Tree is a highly balanced binary tree. The height difference between the two Subtrees on any node <= 1

 

Implement AVL Tree

Define an AVL Tree, AVLTree, and AVLNode, which has the following features:

1. key -- Keyword: sorts nodes in the AVL Tree.

2. left -- left subtree

3. right -- right subtree

4. height -- height

 

If a node is inserted into the AVL Tree, the AVL tree may be out of balance. There are four statuses:

LL: Left left, LeftLeft

LR: Left and Right, LeftRight

RL: Right left, RightLeft

RR: Right right, RightRight

 

Solve the problem above

Solve LL, which requires a single left Rotation

Solve RR, right single rotation required

To solve the LR problem, you must first rotate the right one and then rotate the right one.

To solve RL, you must first rotate the left and then rotate the right

 

Achieve left single rotation

 

 

K1, k2

Left of k2 to k1

Right of k1 to left of k2

K2 gives k1 the right

 

Achieve right single rotation

K1, k2

K1 right to k2

Left of k2 to right of k1

Left of k1 to k2

 

 

 

The height of a node is the one in the left or right subtree.

 

/*** AVL Tree test * @ author taoshihan * @ param <T> **/public class AVLTree <T extends Comparable <T> {private AVLNode mRoot; // root node class AVLNode <T extends Comparable <T> {private T key; // key value private int height; // height private AVLNode left; // left subtree private AVLNode right; // right subtree public AVLNode (T key, AVLNode left, AVLNode right) {this. key = key; this. left = left; this. right = right; this. height = 0 ;}/ *** get node height * @ par Am tree * @ return */public int height (AVLNode <T> tree) {if (tree! = Null) {return tree. height;} return 0;}/*** retrieve the * @ param a * @ param B * @ return */public int maxHeight (int, int B) {return a> B? A: B;}/*** left single rotation * @ param k2 * @ return */public AVLNode <T> leftLeftRotation (AVLNode <T> k2) {AVLNode k1; k1 = k2.left; k2.left = k1.right; k1.right = k2; k2.height = maxHeight (height (k2.left), height (k2.right); k1.height = maxHeight (height (k1.left ), height (k1.right); return k1;}/*** right single rotation * @ param k2 * @ return */public AVLNode <T> rightRightRotation (AVLNode <T> k1) {AVLNode k2; k2 = k1.right; k1.right = k2.left; k2.left = k1; k2.height = maxHeight (k2.left), height (k2.right); k1.height = maxHeight (height (k1.left ), height (k1.right); return k2 ;}