const m=3;n=4;
var a:array[1..m,1..n] of integer;
i,j:integer;
begin
for i:=1 to m do
for j:=1 to n do
begin
if odd(j) then a[i,j]:=i+(j-1)*m else a[i,j]:=j*m-i+1;
if j end;
end.
Замените odd на mod

спасибо

const m=3;n=4;var a:array[1..m,1..n] of integer;i,j:integer;beginfor i:=1 to m dofor j:=1 to n dobeginif j mod 2<>0 then a[i,j]:=i+(j-1)*m else a[i,j]:=j*m-i+1;if j end;end.