如何实现红黑树？

红黑树是一种自平衡二叉查找树，它通过对节点进行着色和旋转操作保持树的平衡，从而保证了查找、插入和删除操作的时间复杂度均为$O(logn)$，其中$n$为树中节点的数量。

下面是红黑树的Java实现：

public class RedBlackTree<K extends Comparable<K>, V> {
    private static final boolean RED = true;
    private static final boolean BLACK = false;

    private Node root;

    private class Node {
        K key;
        V value;
        Node left, right;
        boolean color;
        int size;

        public Node(K key, V value, boolean color, int size) {
            this.key = key;
            this.value = value;
            this.color = color;
            this.size = size;
        }
    }

    private boolean isRed(Node x) {
        if (x == null) {
            return false;
        }
        return x.color == RED;
    }

    private int size(Node x) {
        if (x == null) {
            return 0;
        }
        return x.size;
    }

    public int size() {
        return size(root);
    }

    public V get(K key) {
        Node x = root;
        while (x != null) {
            int cmp = key.compareTo(x.key);
            if (cmp < 0) {
                x = x.left;
            } else if (cmp > 0) {
                x = x.right;
            } else {
                return x.value;
            }
        }
        return null;
    }

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

    private Node put(Node h, K key, V value) {
        if (h == null) {
            return new Node(key, value, RED, 1);
        }
        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.size = size(h.left) + size(h.right) + 1;
        return h;
    }

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

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

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