bool move(int tile)
{
    for (int row = 0; row <= d-1; row++) {
        for (int column = 0; column <= d-1; column++) {
            if (board[row][column] == 0)
            {
                if (board[row-1][column] == tile) // valid move swap with up
                {
                    board[row][column] = tile;
                    board[row-1][column] = 0;
                    return true;
                } else if (board[row+1][column] == tile) // valid move swap with down
                {
                    board[row][column] = tile;
                    board[row+1][column] = 0;
                    return true;
                } else if (board[row][column-1] == tile) // valid move swap with left
                {
                    board[row][column] = tile;
                    board[row][column-1] = 0;
                    return true;
                } else if (board[row][column+1] == tile) // valid move swap with right
                {
                    board[row][column] = tile;
                    board[row][column+1] = 0;
                    return true;
                }

            }
        }
    }
    return true;
}