class SudokuGrid
    {
        private GridSquare[,] GridCell = new GridSquare[10,10];
        private int[,] GridRefs = { { 1, 1 }, { 1, 4 }, { 1, 7 }, { 4, 1 }, { 4, 4 }, { 4, 7 }, { 7, 1 }, { 7, 4 }, { 7, 7 } };

        public SudokuGrid()
        {
            for (int i = 1; i <= 9; i++)
            {
                for (int j = 1; j <= 9; j++)
                {
                    GridCell[i, j] = new GridSquare(i, j);
                }
            }
        }
        public GridSquare this[int i, int j]
        {
            get { return GridCell[i, j]; }
        }
        public void EnterItem(int row, int col, int cellvalue)
        {
            GridCell[row, col].Value = cellvalue;
            //eliminate from columns and rows
            for (int i = 1; i <= 9; i++)
            {
                if (i != row)
                {
                    GridCell[row, i][cellvalue] = 1;
                }
                if (i != col)
                {
                    GridCell[i,col][cellvalue] = 1;
                }
            }
            //eliminate from minisquares
            for (int i = GridRefs[GridCell[row, col].MiniSquare, 0]; i <= GridRefs[GridCell[row, col].MiniSquare, 0] + 2; i++)
            {
                for (int j = GridRefs[GridCell[row, col].MiniSquare, 1]; j <= GridRefs[GridCell[row, col].MiniSquare, 1] + 2; j++)
                {
                    GridCell[i, j][cellvalue] = 1;
                }
            }
        }
    }