const int N = 4;//按钮的行、列数
        Button[,] buttons = new Button[N, N];//按钮的数组
        int step = 0;//记录步数

        private void Form3_Load(object sender, EventArgs e)
        {
            //产生所有按钮
            GenerateAllButtons();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //打乱顺序
            this.button1.Text = "重新开始";
            Shuffle();
        }
        void GenerateAllButtons()
        {
            int x0 = 100, y0 = 10, w = 45, d = 50;
            for (int r = 0; r < N; r++)
            {
                for (int c = 0; c < N; c++)
                {
                    int num = r * N + c;
                    Button btn = new Button();
                    btn.Text = (num + 1).ToString();
                    btn.Top = y0 + r * d;
                    btn.Left = x0 + c * d;
                    btn.Width = w;
                    btn.Height = w;
                    btn.Visible = true;
                    btn.Tag = num;
                    //注册事件
                    btn.Click += new EventHandler(Btn_Click);
                    buttons[r, c] = btn; //放到数组中
                    this.Controls.Add(btn); //加到界面上
                }
            }
            buttons[N - 1, N - 1].Visible = false;//最后一个btn不可见面
        }

       
        private void Btn_Click(object sender, EventArgs e)
        {
            step++;
            Button btn = sender as Button;//当前选中的按钮
            Button blank = FindHiddenButton();//空白的按钮
            //判断是否与空白块相邻，如果是，则交换
            if (IsNeighbor(btn, blank))
            {
                Swap(btn, blank);
                blank.Focus();
            }
            //判断是否完成了
            if (ResultIsOk())
            {
                string result = "你真棒！"+"\n一共用了"+step.ToString()+"步";
                MessageBox.Show(result);
            }

        }
        Button FindHiddenButton()
        {
            for (int r = 0; r < N; r++)
            {
                for (int c = 0; c < N; c++)
                {
                    if (!buttons[r, c].Visible)
                    {
                        return buttons[r, c];
                    }
                }
            }
            return null;
        }
        bool IsNeighbor(Button btnA, Button btnB)
        {
            int a = (int)btnA.Tag;//获得按钮记录的值
            int b = (int)btnB.Tag;
            int r1 = a / N;int c1 = a % N;//得到按钮的行号和列号
            int r2 = b / N; int c2 = b % N;
            if ((r1 == r2 && (c1 - c2 == 1 || c2 - c1 == 1))//左右相邻
                || (c1 == c2 && (r1 - r2 == 1 || r2 - r1 == 1))//上下相邻
                )
                {
                return true;
            }
            return false;
        }
        //检查是否完成
        bool ResultIsOk()
        {
            for (int r = 0; r < N; r++)
                for (int c = 0; c < N; c++)
                {
                    if (buttons[r, c].Text != (r * N + c + 1).ToString())
                    {
                        return false;
                    }
                }
            return true;
        }
        //打乱顺序
        void Shuffle()
        {
            //多次随机交换两个按钮
            Random rnd = new Random();
            for (int i = 0; i < 100; i++)
            {
                int a = rnd.Next(N);
                int b = rnd.Next(N);
                int c = rnd.Next(N);
                int d = rnd.Next(N);
                Swap(buttons[a, b], buttons[c, d]);
            }
        }
        //交换两个按钮
        void Swap(Button btna, Button btnb)
        {
            string t = btna.Text;
            btna.Text = btnb.Text;
            btnb.Text = t;

            bool v = btna.Visible;
            btna.Visible = btnb.Visible;
            btnb.Visible = v;
        }
    }