数据结构 玩转数据结构 13-5 保持根节点为黑色和左旋转

//1     定义Node
    class Node{
        private K key;
        private V value;
        private Node left,right;
        private int height;
        private boolean color;

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

        @Override
        public String toString() {
            final StringBuffer sb = new StringBuffer("Node{");
            sb.append("key=").append(key);
            sb.append(", value=").append(value);
            sb.append('}');
            return sb.toString();
        }
    }

    /**
     * 添加节点后根节点设置为黑色
     * @author weidoudou
     * @date 2023/5/5 7:01
     * @param key 请添加参数描述
     * @param  value 请添加参数描述
     * @return void
     **/
    public void add(K key, V value) {
        root = add(key,value,root);
        root.color = BLACK;
    }

    //   node                     x
    //  /   \     左旋转         /  \
    // T1   x   --------->   node   T3
    //     / \              /   \
    //    T2 T3            T1   T2
    private Node leftRotate(Node node) {
        Node x = node.right;
        Node T2 = x.left;

        // 向左旋转过程
        node.right = T2;
        x.left = node;

        // 更新color
        x.color = node.color;
        node.color = RED;

        return x;
    }