红黑树

package com.zhangyong.DataStructures.Tree.RedBlackTree;
import com.zhangyong.DataStructures.Tree.AVL.FileOperation;
import java.util.ArrayList;
public class RBTree<K extends Comparable<K>, V> {
    private static final boolean RED = true;
    private static final boolean BLACK = false;
    private class Node {
        public K key;
        public V value;
        public Node left, right;
        public boolean color;
        public Node(K key, V value) {
            this.key = key;
            this.value = value;
            left = null;
            right = null;
            color = RED;
        }
    }
    private Node root;
    private int size;
    public RBTree() {
        root = null;
        size = 0;
    }
    public int getSize() {
        return size;
    }
    public boolean isEmpty() {
        return size == 0;
    }
    // 判断节点node的颜色
    private boolean isRed(Node node) {
        if (node == null)
            return BLACK;
        return node.color;
    }
    /**
     * a                       c
     * /  \                    /   \
     * b    c     ===>         a    e
     * /  \               /  \    \
     * d    e             b   d     f
     * \
     * f
     * 左旋转
     */
    private Node leftRotate(Node node) {
        Node x = node.right;
        node.right = x.left;
        x.left = node;
        x.color = node.color;
        node.color = RED;
        return x;
    }
    /**
     *             a                   b
     *           /  \               /     \
     *          b    c ===>        d       a
     *        /  \               /       /  \
     *       d   e              f       e    c
     *     /
     *    f
     */
    private Node rightRotate(Node node) {
        Node x = node.left;
        node.left = x.right;
        x.right = node;
        x.color = node.color;
        node.color = RED;
        return x;
    }
    /**
     * 颜色翻转
     *
     * @param node
     */
    private void flipColor(Node node) {
        node.color = RED;
        node.left.color = BLACK;
        node.right.color = BLACK;
    }
    // 向二分搜索树中添加新的元素(key, value)
    public void add(K key, V value) {
        root = add(root, key, value);
        root.color = BLACK; //保持最终的根节点为黑色;
    }
    // 向以node为根的红黑树中插入元素(key, value)，递归算法
    // 返回插入新节点后红黑树的根
    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 // key.compareTo(node.key) == 0
            node.value = value;
        if (isRed(node.right) && !isRed(node.left)) {
            node = leftRotate(node);
        }
        if (isRed(node.left) && isRed(node.left.left)) {
            node = rightRotate(node);
        }
        if (isRed(node.left) && isRed(node.right)) {
            flipColor(node);
        }
        return node;
    }
    // 返回以node为根节点的二分搜索树中，key所在的节点
    private Node getNode(Node node, K key) {
        if (node == null)
            return null;
        if (key.equals(node.key))
            return node;
        else if (key.compareTo(node.key) < 0)
            return getNode(node.left, key);
        else // if(key.compareTo(node.key) > 0)
            return getNode(node.right, key);
    }
    public boolean contains(K key) {
        return getNode(root, key) != null;
    }
    public V get(K key) {
        Node node = getNode(root, key);
        return node == null ? null : node.value;
    }
    public void set(K key, V newValue) {
        Node node = getNode(root, key);
        if (node == null)
            throw new IllegalArgumentException(key + " doesn't exist!");
        node.value = newValue;
    }
    // 返回以node为根的二分搜索树的最小值所在的节点
    private Node minimum(Node node) {
        if (node.left == null)
            return node;
        return minimum(node.left);
    }
    // 删除掉以node为根的二分搜索树中的最小节点
    // 返回删除节点后新的二分搜索树的根
    private Node removeMin(Node node) {
        if (node.left == null) {
            Node rightNode = node.right;
            node.right = null;
            size--;
            return rightNode;
        }
        node.left = removeMin(node.left);
        return node;
    }
    // 从二分搜索树中删除键为key的节点
    public V remove(K key) {
        Node node = getNode(root, key);
        if (node != null) {
            root = remove(root, key);
            return node.value;
        }
        return null;
    }
    private Node remove(Node node, K key) {
        if (node == null)
            return null;
        if (key.compareTo(node.key) < 0) {
            node.left = remove(node.left, key);
            return node;
        } else if (key.compareTo(node.key) > 0) {
            node.right = remove(node.right, key);
            return node;
        } else {   // key.compareTo(node.key) == 0
            // 待删除节点左子树为空的情况
            if (node.left == null) {
                Node rightNode = node.right;
                node.right = null;
                size--;
                return rightNode;
            }
            // 待删除节点右子树为空的情况
            if (node.right == null) {
                Node leftNode = node.left;
                node.left = null;
                size--;
                return leftNode;
            }
            // 待删除节点左右子树均不为空的情况
            // 找到比待删除节点大的最小节点, 即待删除节点右子树的最小节点
            // 用这个节点顶替待删除节点的位置
            Node successor = minimum(node.right);
            successor.right = removeMin(node.right);
            successor.left = node.left;
            node.left = node.right = null;
            return successor;
        }
    }
    public static void main(String[] args) {
        System.out.println("Pride and Prejudice");
        ArrayList<String> words = new ArrayList<>();
        if (FileOperation.readFile("pride-and-prejudice.txt", words)) {
            System.out.println("Total words: " + words.size());
            RBTree<String, Integer> map = new RBTree<>();
            for (String word : words) {
                if (map.contains(word))
                    map.set(word, map.get(word) + 1);
                else
                    map.add(word, 1);
            }
            System.out.println("Total different words: " + map.getSize());
            System.out.println("Frequency of PRIDE: " + map.get("pride"));
            System.out.println("Frequency of PREJUDICE: " + map.get("prejudice"));
        }
        System.out.println();
    }
}