AVLTree.java

import java.util.ArrayList;
import java.util.LinkedList;
import java.util.Queue;
import java.util.Stack;

/**
 * Author : 13152
 * Date : 2020/2/10
 * Time : 9:54
 * Version ： 1.0.0
 **/
public class AVLTree<K extends Comparable<K>, V> {

    private class Node{  //内部类
        public K key;
        public V value;
        public Node left, right;
        public int height;

        public Node(K key, V value){
            this.key = key;
            this.value = value;
            left = null;
            right = null;
            height = 1;
        }

        @Override
        public String toString() {
            return key.toString() + ":" + value.toString();
        }
    }
    private Node root;
    private int size;


    public AVLTree(){
        root = null;
        size = 0;
    }

    private Node getNode(K key) {
        return getNode(root, key);
    }

    private Node getNode(Node node, K key) {
        if (node == null)
            return null;

        if (node.key.compareTo(key) < 0)
            return getNode(node.left, key);
        else if (node.key.compareTo(key) > 0)
            return getNode(node.right, key);
        else
            return node;
    }

    public boolean isBST(){
        ArrayList<K> keys = new ArrayList<>();
        inOrder(root, keys);
        for (int i = 1; i < keys.size(); i++)
            if (keys.get(i - 1).compareTo(keys.get(i)) > 0)
                return false;
        return true;
    }

    public boolean isBalance() {
        return isBalance(root);
    }

    private boolean isBalance(Node node) {
        if (node == null)
            return true;

        int balanceFactor = getBalanceFactor(node);
        if (Math.abs(balanceFactor) > 1)
            return false;
        return isBalance(node.left) && isBalance(node.right);
    }

    private void inOrder(Node node, ArrayList<K> keys) {
        if (node == null)
            return;
        inOrder(node.left, keys);
        keys.add(node.key);
        inOrder(node.right, keys);
    }
    private int getHeight(Node node) {
        if (node == null)
            return 0;
        return node.height;
    }

    private int getBalanceFactor(Node node){
        if (node == null)
            return 0;
        return getHeight(node.left) - getHeight(node.right);
    }

    private Node rightRotate(Node y) {
        Node x = y.left;
        Node T3 = x.right;

        x.right = y;
        y.left = T3;

        y.height = Math.max(getHeight(y.left), getHeight(y.right)) + 1;
        x.height = Math.max(getHeight(x.left), getHeight(x.right)) + 1;

        return x;
    }

    private Node leftRotate(Node y) {

        Node x = y.right;
        Node T3 = x.left;

        x.left = y;
        y.right = T3;

        y.height = Math.max(getHeight(y.left), getHeight(y.right)) + 1;
        x.height = Math.max(getHeight(x.left), getHeight(x.right)) + 1;

        return x;
    }

    public void add(K key, V value) {
        add(root, key, value);
    }

    private Node add(Node node, K key, V value) {
        if (node == null){
            size++;
            return new Node(key, value);
        }
        if (key.compareTo(node.key) < 0)
            node.left = add(node.left, key, value);
        else if (key.compareTo(node.key) > 0)
            node.right = add(node.right, key, value);
        else
            node.value = value;

        node.height = 1 + Math.max(getHeight(node.left), getHeight(node.right));

        int balanceFactor = getBalanceFactor(node);
        if (Math.abs(balanceFactor) > 1)
            System.out.println("unbalance : " + balanceFactor);

        // LL
        if (balanceFactor > 1 && getBalanceFactor(node.left) >= 0)
            return rightRotate(node);

        // RR
        if (balanceFactor < -1 && getBalanceFactor(node.right) <= 0)
            return leftRotate(node);

        // LR
        if (balanceFactor > 1 && getBalanceFactor(node.left) < 0){
            node.left = leftRotate(node.left);
            return rightRotate(node);
        }

        // RL
        if (balanceFactor < -1 && getBalanceFactor(node.right) > 0){
            node.right = rightRotate(node.right);
            return leftRotate(node);
        }

        return node;
    }


    public boolean contains(K key) {
        return getNode(key) != null;
    }


    public V get(K key) {
        Node node = getNode(key);
        return node == null ? null : node.value;
    }

    public void set(K key, V newValue) {
        Node node = getNode(key);
        if (node != null)
            node.value = newValue;
        else
            throw new IllegalArgumentException(key + "doesn't exist");
    }


    private Node minimum(Node node) {
        if (node.left == null)
            return node;
        return minimum(node.left);
    }

    public V remove(K key) {
        return remove(root, key).value;
    }

    private Node remove(Node node, K key) {
        if (node == null)
            return null;
        Node retNode;
        if (key.compareTo(node.key) < 0) {
            node.left = remove(node.left, key);
            retNode = node;
        } else if (key.compareTo(node.key) > 0) {
            node.right = remove(node.right, key);
            retNode = node;
        } else {
            if (node.left == null) {
                Node rightNode = node.right;
                node.right = null;
                size--;
                retNode = rightNode;
            }
            else if (node.right == null) {
                Node leftNode = node.left;
                node.left = null;
                size--;
                retNode = leftNode;
            }
            else {
            Node successor = minimum(node.right);
            successor.right = remove(node.right, successor.key);
            successor.right = node.left;
            node.left = node.right = null;
            retNode = successor;
            }
        }

        if (retNode == null)
            return null;
        retNode.height = 1 + Math.max(getHeight(retNode.left), getHeight(retNode.right));

        int balanceFactor = getBalanceFactor(retNode);
        // LL
        if (balanceFactor > 1 && getBalanceFactor(retNode.left) >= 0)
            return rightRotate(retNode);

        // RR
        if (balanceFactor < -1 && getBalanceFactor(retNode.right) <= 0)
            return leftRotate(retNode);

        // LR
        if (balanceFactor > 1 && getBalanceFactor(retNode.left) < 0){
            retNode.left = leftRotate(retNode.left);
            return rightRotate(retNode);
        }

        // RL
        if (balanceFactor < -1 && getBalanceFactor(retNode.right) > 0){
            retNode.right = rightRotate(retNode.right);
            return leftRotate(retNode);
        }

        return retNode;
    }

    public int getSize() {
        return size;
    }


    public boolean isEmpty() {
        return size == 0;
    }

    public static void main(String[] args) {
        BST<Integer> bst = new BST<Integer>();
        bst.add(10);
        bst.add(3);
        bst.add(5);
        bst.add(2);
        bst.add(12);
        bst.add(15);
        bst.add(11);

        System.out.println(bst.contains(1));

        bst.preOrder();
        System.out.println();

        bst.preOrderNR();
        System.out.println("inOrder");

        bst.inOrder();
        System.out.println();

        bst.lastOrder();
        System.out.println();

        bst.levelOrder();

        System.out.println();
        bst.removeMinimum();

        bst.levelOrder();

        System.out.println();
        bst.minimum();
    }
}