Automating table creation

This creates the same table as yours. The \TypesetTable command has also an optional argument for setting the threshold on the number of columns, see the example.

\documentclass{article}
\usepackage[a4paper,margin=1cm]{geometry}
\usepackage{xparse,booktabs}

\ExplSyntaxOn
\NewDocumentCommand{\TypesetTable}{ O{10} m }
 {
  \nebu_typeset_table:nn { #1 } { #2 }
 }

\keys_define:nn { nebutable }
 {
  Del1 .tl_set:N = \l__nebu_deli_tl,
  PDel1 .tl_set:N = \l__nebu_pdeli_tl,
  Del2 .tl_set:N = \l__nebu_delii_tl,
  PDel2 .tl_set:N = \l__nebu_pdelii_tl,
 }

\int_new:N \l__nebu_columns_int
\int_new:N \l__nebu_pdeli_total_int
\int_new:N \l__nebu_pdelii_total_int
\int_new:N \l_nebu_countrows_int
\seq_new:N \l__nebu_deli_seq
\seq_new:N \l__nebu_pdeli_seq
\seq_new:N \l__nebu_delii_seq
\seq_new:N \l__nebu_pdelii_seq
\tl_new:N \l__nebu_preamble_tl
\tl_new:N \l__nebu_table_body_tl

\cs_new_protected:Npn \nebu_typeset_table:nn #1 #2
 {
  \keys_set:nn { nebutable } { #2 }
  \seq_set_split:NnV \l__nebu_deli_seq { , } \l__nebu_deli_tl
  \seq_set_split:NnV \l__nebu_pdeli_seq { , } \l__nebu_pdeli_tl
  \seq_set_split:NnV \l__nebu_delii_seq { , } \l__nebu_delii_tl
  \seq_set_split:NnV \l__nebu_pdelii_seq { , } \l__nebu_pdelii_tl
  % Compute the number of inner columns
  \int_set:Nn \l__nebu_columns_int
   {
    \int_min:nn { #1 }
     {
      \int_max:nn { \seq_count:N \l__nebu_deli_seq }
                  { \seq_count:N \l__nebu_delii_seq }
     }
   }
  % Define the table preamble
  \tl_set:Nx \l__nebu_preamble_tl
   { l c *{ \int_to_arabic:n { \l__nebu_columns_int } } { c } c }
  % Compute the total for Del1
  \int_zero:N \l__nebu_pdeli_total_int
  \seq_map_inline:Nn \l__nebu_pdeli_seq
   { \int_set:Nn \l__nebu_pdeli_total_int { \l__nebu_pdeli_total_int + ##1 } }
  % Compute the total for Del2
  \int_zero:N \l__nebu_pdelii_total_int
  \seq_map_inline:Nn \l__nebu_pdelii_seq
   { \int_set:Nn \l__nebu_pdelii_total_int { \l__nebu_pdelii_total_int + ##1 } }
  % Start building the table contents
  \tl_clear:N \l__nebu_table_body_tl
  \tl_put_right:Nx \l__nebu_table_body_tl
   { \exp_not:N \multicolumn { \int_to_arabic:n { \l__nebu_columns_int + 2 } } { c } { } }
  \tl_put_right:Nn \l__nebu_table_body_tl { & Sum \\ \midrule }

  % Insert Del1
  \__nebu_insert_table_part:nn { deli } { Del~1 }
  \tl_put_right:Nn \l__nebu_table_body_tl { \midrule }
  % Insert Del2
  \__nebu_insert_table_part:nn { delii } { Del~2 }

  % Add total
  \tl_put_right:Nx \l__nebu_table_body_tl
   {
    \exp_not:N \midrule
    \exp_not:N \multicolumn
                { \int_to_arabic:n { 2 + \l__nebu_columns_int } }
                { r }
                { Total~antall~poeng }
    &
    \int_to_arabic:n { \l__nebu_pdeli_total_int + \l__nebu_pdelii_total_int }
    \exp_not:N \\
   }

  % Print the table
  \use:x{ \exp_not:N \begin{tabular}{\l__nebu_preamble_tl} }
  \toprule
  \l__nebu_table_body_tl
  \bottomrule
  \end{tabular}
}

\cs_new_protected:Npn \__nebu_insert_table_part:nn #1 #2
 {
  \int_set:Nn \l_nebu_countrows_int
   {
    \seq_count:c { l__nebu_#1_seq } / \l__nebu_columns_int
   }
  \int_step_inline:nnnn { 1 } { 1 } { \l_nebu_countrows_int }
   {
    % First line
    \int_compare:nTF { ##1 = 1 }
     {
      \tl_put_right:Nn \l__nebu_table_body_tl { #2 & Oppgave & }
     }
     {
      \tl_put_right:Nx \l__nebu_table_body_tl
       { \exp_not:N \cmidrule{3-\int_to_arabic:n { \l__nebu_columns_int + 3 }} }
      \tl_put_right:Nn \l__nebu_table_body_tl { & & }
     }
    \int_step_inline:nnnn 
     { (##1 - 1)*\l__nebu_columns_int + 1 } 
     { 1 }
     { ##1 * \l__nebu_columns_int }
     {
      \tl_put_right:Nx \l__nebu_table_body_tl 
       { \seq_item:cn { l__nebu_#1_seq } { ####1 } & }
     }
     \tl_put_right:Nn \l__nebu_table_body_tl { \\ }
     % Second line
    \int_compare:nTF { ##1 = 1 }
     { \tl_put_right:Nn \l__nebu_table_body_tl { & Poeng & } }
     { \tl_put_right:Nn \l__nebu_table_body_tl { & & } }
     \int_step_inline:nnnn 
      { (##1 - 1)*\l__nebu_columns_int + 1 }
      { 1 }
      { ##1 * \l__nebu_columns_int }
      {
       \tl_put_right:Nx \l__nebu_table_body_tl
        { \seq_item:cn { l__nebu_p#1_seq } { ####1 } & }
      }
      \tl_put_right:Nx \l__nebu_table_body_tl
       {
        \int_compare:nT { ##1 = 1 }
         { \int_to_arabic:n { \use:c { l__nebu_p#1_total_int } } }
        \exp_not:N \\
       }
   }
 }

\ExplSyntaxOff

\setlength{\parindent}{0pt} % just for the example

\begin{document}

\TypesetTable{
  Del1= {1a1,1a2,1a3,1b1,1b2,1b3,1c,1d1,1d2,1d3,1e1,1e2,1f,1g1,1g2,1g3},
  PDel1={1,  1,  1,  1,  2,  2,  2, 2,  0,  2,  2,  2,  2, 2,  2,  0},
  Del2= {2a,2b,2c,2d,2e,2f,3a1,3a2,3b,4a,4b,4c,4d,5a,5b,5c,6a,6b},
  PDel2={2, 2, 2, 2, 2, 2, 2,  2,  3, 2, 2, 2, 2, 1, 2, 2, 2, 2}
}

\bigskip

\TypesetTable[8]{
  Del1= {1a1,1a2,1a3,1b1,1b2,1b3,1c,1d1,1d2,1d3,1e1,1e2,1f,1g1,1g2,1g3},
  PDel1={1,  1,  1,  1,  2,  2,  2, 2,  0,  2,  2,  2,  2, 2,  2,  0},
  Del2= {2a,2b,2c,2d,2e,2f,3a1,3a2,3b,4a,4b,4c,4d,5a,5b,5c,6a,6b},
  PDel2={2, 2, 2, 2, 2, 2, 2,  2,  3, 2, 2, 2, 2, 1, 2, 2, 2, 2}
}


\end{document}

---

This is a new implementation that allows to gather the exercises label and grades during the document and print the table anywhere; it requires two runs before stabilizing, as it uses the .aux file.

The \addtoDel macro receives three arguments; the first is 1 or 2, for the two kinds, the second is the label and the third is the grade. You'll probably be using it in the macro for typesetting the exercises.

The new \TypesetTable command has only one optional argument to set the threshold number of inner columns.

\documentclass{article}
\usepackage[a4paper,margin=1cm]{geometry}
\usepackage{xparse,booktabs}

\ExplSyntaxOn

\NewDocumentCommand{\TypesetTable} { O{10} }
 {
  \seq_if_empty:NT \g__nebu_deli_seq
   {
    \seq_gput_right:Nn \g__nebu_deli_seq { X }
    \seq_gput_right:Nn \g__nebu_pdeli_seq { 0 }
    \seq_gput_right:Nn \g__nebu_delii_seq { X }
    \seq_gput_right:Nn \g__nebu_pdelii_seq { 0 }
   }
  \nebu_typeset_table:n { #1 }
 }

\NewDocumentCommand{\addtoDel}{mmm}
 {
  \clist_gput_right:cn { g__nebu_del\int_to_roman:n { #1 }_clist } { #2 }
  \clist_gput_right:cn { g__nebu_pdel\int_to_roman:n { #1 }_clist } { #3 }
 }

\AtEndDocument{
  \iow_shipout:cx { @auxout }
   { \exp_not:N \LoadDel { i } { \g__nebu_deli_clist } }
  \iow_shipout:cx { @auxout }
   { \exp_not:N \LoadPDel { i } { \g__nebu_pdeli_clist } }
  \iow_shipout:cx { @auxout }
   { \exp_not:N \LoadDel { ii } { \g__nebu_delii_clist } }
  \iow_shipout:cx { @auxout }
   { \exp_not:N \LoadPDel { ii } { \g__nebu_pdelii_clist } }
}
\cs_generate_variant:Nn \iow_shipout:Nx { c }
\NewDocumentCommand{\LoadDel}{mm}
 {
  \seq_gset_split:cnn { g__nebu_del#1_seq } { , } { #2 }
 }
\NewDocumentCommand{\LoadPDel}{mm}
 {
  \seq_gset_split:cnn { g__nebu_pdel#1_seq } { , } { #2 }
 }
\cs_generate_variant:Nn \seq_gset_split:Nnn { c }

\int_new:N \l__nebu_columns_int
\int_new:N \l__nebu_pdeli_total_int
\int_new:N \l__nebu_pdelii_total_int
\int_new:N \l_nebu_countrows_int
\seq_new:N \g__nebu_deli_seq
\seq_new:N \g__nebu_pdeli_seq
\seq_new:N \g__nebu_delii_seq
\seq_new:N \g__nebu_pdelii_seq
\clist_new:N \g__nebu_deli_clist
\clist_new:N \g__nebu_pdeli_clist
\clist_new:N \g__nebu_delii_clist
\clist_new:N \g__nebu_pdelii_clist
\tl_new:N \l__nebu_preamble_tl
\tl_new:N \l__nebu_table_body_tl

\cs_new_protected:Npn \nebu_typeset_table:n #1
 {
  % Compute the number of inner columns
  \int_set:Nn \l__nebu_columns_int
   {
    \int_min:nn { #1 }
     {
      \int_max:nn { \seq_count:N \g__nebu_deli_seq }
                  { \seq_count:N \g__nebu_delii_seq }
     }
   }
  % Define the table preamble
  \tl_set:Nx \l__nebu_preamble_tl
   { l c *{ \int_to_arabic:n { \l__nebu_columns_int } } { c } c }
  % Compute the total for Del1
  \int_zero:N \l__nebu_pdeli_total_int
  \seq_map_inline:Nn \g__nebu_pdeli_seq
   { \int_set:Nn \l__nebu_pdeli_total_int { \l__nebu_pdeli_total_int + ##1 } }
  % Compute the total for Del2
  \int_zero:N \l__nebu_pdelii_total_int
  \seq_map_inline:Nn \g__nebu_pdelii_seq
   { \int_set:Nn \l__nebu_pdelii_total_int { \l__nebu_pdelii_total_int + ##1 } }
  % Start building the table contents
  \tl_clear:N \l__nebu_table_body_tl
  \tl_put_right:Nx \l__nebu_table_body_tl
   { \exp_not:N \multicolumn { \int_to_arabic:n { \l__nebu_columns_int + 2 } } { c } { } }
  \tl_put_right:Nn \l__nebu_table_body_tl { & Sum \\ \midrule }

  % Insert Del1
  \__nebu_insert_table_part:nn { deli } { Del~1 }
  \tl_put_right:Nn \l__nebu_table_body_tl { \midrule }
  % Insert Del2
  \__nebu_insert_table_part:nn { delii } { Del~2 }

  % Add total
  \tl_put_right:Nx \l__nebu_table_body_tl
   {
    \exp_not:N \midrule
    \exp_not:N \multicolumn
                { \int_to_arabic:n { 2 + \l__nebu_columns_int } }
                { r }
                { Total~antall~poeng }
    &
    \int_to_arabic:n { \l__nebu_pdeli_total_int + \l__nebu_pdelii_total_int }
    \exp_not:N \\
   }

  % Print the table
  \use:x{ \exp_not:N \begin{tabular}{\l__nebu_preamble_tl} }
  \toprule
  \l__nebu_table_body_tl
  \bottomrule
  \end{tabular}
}

\cs_new_protected:Npn \__nebu_insert_table_part:nn #1 #2
 {
  \int_set:Nn \l_nebu_countrows_int
   {
    \seq_count:c { g__nebu_#1_seq } / \l__nebu_columns_int
   }
  \int_step_inline:nnnn { 1 } { 1 } { \l_nebu_countrows_int }
   {
    % First line
    \int_compare:nTF { ##1 = 1 }
     {
      \tl_put_right:Nn \l__nebu_table_body_tl { #2 & Oppgave & }
     }
     {
      \tl_put_right:Nx \l__nebu_table_body_tl
       { \exp_not:N \cmidrule(lr){3-\int_to_arabic:n { \l__nebu_columns_int + 2 }} }
      \int_compare:nT { ##1 = 2 }
       {\tl_put_right:Nx \l__nebu_table_body_tl
         { \exp_not:N \cmidrule(l{3em}r)
            {\int_to_arabic:n { \l__nebu_columns_int + 2 }-
             \int_to_arabic:n { \l__nebu_columns_int + 3 }}
         }
       }
      \tl_put_right:Nn \l__nebu_table_body_tl { & & }
     }
    \int_step_inline:nnnn 
     { (##1 - 1)*\l__nebu_columns_int + 1 } 
     { 1 }
     { ##1 * \l__nebu_columns_int }
     {
      \tl_put_right:Nx \l__nebu_table_body_tl 
       { \seq_item:cn { g__nebu_#1_seq } { ####1 } & }
     }
     \tl_put_right:Nn \l__nebu_table_body_tl { \\ }
     % Second line
    \int_compare:nTF { ##1 = 1 }
     { \tl_put_right:Nn \l__nebu_table_body_tl { & Poeng & } }
     { \tl_put_right:Nn \l__nebu_table_body_tl { & & } }
     \int_step_inline:nnnn 
      { (##1 - 1)*\l__nebu_columns_int + 1 }
      { 1 }
      { ##1 * \l__nebu_columns_int }
      {
       \tl_put_right:Nx \l__nebu_table_body_tl
        { \seq_item:cn { g__nebu_p#1_seq } { ####1 } & }
      }
      \tl_put_right:Nx \l__nebu_table_body_tl
       {
        \int_compare:nT { ##1 = 1 }
         { \int_to_arabic:n { \use:c { l__nebu_p#1_total_int } } }
        \exp_not:N \\
       }
   }
 }

\ExplSyntaxOff

\setlength{\parindent}{0pt} % just for the example

\begin{document}

\TypesetTable

\bigskip

\TypesetTable[6]

\addtoDel{1}{1a1}{2}
\addtoDel{1}{1a2}{1}
\addtoDel{1}{1a3}{1}
\addtoDel{1}{1b}{2}
\addtoDel{1}{1c}{2}

\addtoDel{2}{a1}{2}
\addtoDel{2}{a2}{1}
\addtoDel{2}{a3}{1}
\addtoDel{2}{b}{2}
\addtoDel{2}{c}{2}
\addtoDel{2}{d1}{2}
\addtoDel{2}{d2}{2}
\addtoDel{2}{e}{2}
\addtoDel{2}{f1}{2}
\addtoDel{2}{f2}{2}
\addtoDel{2}{f4}{2}
\addtoDel{2}{f5}{2}

\end{document}

I got a bit bored with the formatting but

from

\maketab{
{1a1,1; 1a2,1;1a3,1;1b1,1;1b3,2;1c,2;1d1,2;1d2,2;1d3,0;1e1,2;1e2,2;
     1e3,2;1f,2;1g1,2;1g2,2;1g3,2;}
{2a,2;2b,2;2c,2;2d,2;2e,2;2f,2;3a1,2;3a2,2;3b,3;4a,2;4b,2;
     4c,2;4d,2;5a,1;5b,2;5c,2;6a,2;6b,2;}}

Full document:

\documentclass{article}
\usepackage{array}

\newcount\delcnt
\newcount\thistot
\newcount\tottot
\extrarowheight3pt
\makeatletter

\def\maketab#1{%
\delcnt\z@
\global\tottot\z@
\begin{tabular}{|c|p{20em}|c|}
\@maketab#1\relax
\multicolumn{2}{r|}{Total}&\the\tottot
\end{tabular}}

\def\@maketab#1{%
\ifx\relax#1%
\expandafter\@gobble
\else
\global\thistot\z@
\expandafter\@firstofone
\fi
{\global\advance\delcnt\@ne
Del \the\delcnt&%
\@maketb@#1\relax,;%
&
\global\advance\tottot\thistot
\the\thistot\\\hline\@maketab}}


\def\@maketb@#1,#2;{%
\ifx\relax#1\else
\global\advance\thistot#2\relax
\parbox[t]{2em}{\centering
\strut\ignorespaces#1\par\vskip2pt\hrule\vskip2pt
\strut\ignorespaces#2}\hfil\penalty\z@\hfilneg
\expandafter\@maketb@
\fi}

\makeatother

\begin{document}

\maketab{
{1a1,1; 1a2,1;1a3,1;1b1,1;1b3,2;1c,2;1d1,2;1d2,2;1d3,0;1e1,2;1e2,2;1e3,2;1f,2;1g1,2;1g2,2;1g3,2;}
{2a,2;2b,2;2c,2;2d,2;2e,2;2f,2;3a1,2;3a2,2;3b,3;4a,2;4b,2;4c,2;4d,2;5a,1;5b,2;5c,2;6a,2;6b,2;}}


\end{document}