static bool isSafe(int[,] board, int row, int col)
        {
            int i, j;
            for (i = 0; i < col; i++)
                if (board[row, i] == 1)
                    return false;

            for (i = row, j = col; i >= 0 && j >= 0; i--, j--)
                if (board[i, j] == 1)
                    return false;

            for (i = row, j = col; j >= 0 && i < 8; i++, j--)
                if (board[i, j] == 1)
                    return false;

            return true;
        }

        int l=0;
     
      //  int[,] board = new int[8, 8];
        int[,] big = new int[8, 8];
     

        
        bool solveNQUtil(int[,] board, int col)
        {
          
            if (col >= 8)
            {
             
                for (int i = 0; i < 8; i++)
                {
                    for (int j = 0; j < 8; j++)
                    {

                        big[i, j] = board[i, j];
                    }
                }
              
             
              //  x += 8;
                return true;
            }

            bool res = false;
            for (int i = 0; i < 8; i++)
            {
         
                if (isSafe(board, i, col))
                {
                
                    board[i, col] = 1;

                
    
                    res = solveNQUtil(board, col + 1 ) || res; 

                    board[i, col] = 0; // BACKTRACK  
                }
            }

            return res;
        }
        void solveNQ3()
        {
           int[,] board = new int[8, 8];

          //  solveNQUtil(board, 0);
            if (solveNQUtil(board, 0) == false)
            {
              //  Console.Write("Solution does not exist");
                return ;
            }

            return ;
        }
        public void GoiY()
        {
            solveNQ3();
  /*          for (int i = 0; i < 8; i++)
            {
                for (int j = 0; j < 8; j++)
                {
                    if (Matrix[i][j].BackgroundImage == hinhconco1)
                    {
                      


                      }

                }

            }*/
            for (int row =0; row <8; row++)
            {
                for (int col =0; col <8; col++)
                {
                    if (big[row,col]==1 && Matrix[row][col].BackgroundImage == null)
                    {

                      
                           //if (CheckNonHave(row, col) )
                            {

                                Matrix[row][col].BackgroundImage = hinhconco2;
                                Application.DoEvents();
                                Thread.Sleep(1000);
                                Matrix[row][col].BackgroundImage = null;
                                return;
                            }
                        
                    }
                }
            }
            MessageBox.Show("Không còn đường đi. Bạn đã thua!");
            return;
        }