红黑树实现

package algs4;

/**
 * Created by blank on 2015-10-15 上午10:08.
 */
public class RedBlackTree {

    private Node root;

    public void put(Key key, Value value) {
        root = put(root, key, value);
        root.color = BLACK;
    }

    private Node put(Node h, Key key, Value value) {
        if (h == null) {
            return new Node(key, value, 1, RED);
        }
        int cmp = key.compareTo(h.key);
        if (cmp < 0) {
            h.left = put(h.left, key, value);
        } else if (cmp > 0) {
            h.right = put(h.right, key, value);
        } else {
            h.value = value;
        }
        if (isRed(h.right) && !isRed(h.left)) {
            h = rotateLeft(h);
        }
        if (isRed(h.left) && isRed(h.left.left)) {
            h = rotateRight(h);
        }
        if (isRed(h.left) && isRed(h.right)) {
            flipColors(h);
        }
        h.N = size(h.left) + size(h.right) + 1;
        return h;
    }

    void flipColors(Node h) {
        h.color = RED;
        h.left.color = BLACK;
        h.right.color = BLACK;
    }

    Node rotateLeft(Node h) {
        Node x = h.right;
        h.right = x.left;
        x.left = h;
        x.color = h.color;
        h.color = RED;
        x.N = h.N;
        h.N = 1 + size(h.left) + size(h.right);
        return x;
    }

    Node rotateRight(Node h) {
        Node x = h.left;
        h.left = x.right;
        x.right = h;
        x.color = h.color;
        h.color = RED;
        x.N = h.N;
        h.N = 1 + size(h.left) + size(h.right);
        return x;
    }

    int size(Node x) {
        return x.N;
    }

    static class Key implements Comparable<Key> {
        int val;

        @Override
        public int compareTo(Key o) {
            return val - o.val;
        }
    }

    private boolean isRed(Node x) {
        return x != null && x.color;
    }

    static class Value {
        String val;
    }

    public static final boolean RED = true;

    public static final boolean BLACK = false;
    
    static class Node {
        Key key;
        Value value;
        Node left, right;
        int N;
        boolean color;

        public Node(Key key, Value value, int n, boolean color) {
            this.key = key;
            this.value = value;
            N = n;
            this.color = color;
        }
    }
}