[GAP Forum] Comparison of Length of Lists of list

[Siddiqua Mazhar (PGR)]

Dear Sir/Madam,
 Here I made changes in my previous email, sorry for inconvinience

If I have a list let say a:=[[1,2,3],[4,5],[6,7,8,9],[10,11,12,],[13,14],[15,16,17,18]];

I want to find the list of maximum length in it, or collection of list of max length from above

For instance,  result:=[[6,7,8,9],[15,16,17,18]]; how can i find this result?

here is one algorithm that I tried

>Comparison:=function(a)
>local i,k;
>k:=[];
>  for i in [1..(Length(a)-1)] do
>     if Length(a[i])<Length(a[i+1]) then
>         Add(k,a[i+1]);
>      elif not a[i] in k then
>          Add(k,a[i]);
>     fi;
>  od;
>return k;
>end;

This program works, however , what if two list are of same length next to each other?
for instance a:=[[1,2,3],[4,5],[6,7],[8,9,10]]?

want this result:=[1,2,3],[8,9,10]

or if a:=[[1,2],[3,4],[5,6]] in this case the result wouldl be the same as a because every list are of same length. 

Many thanks.

Kind regards
Siddiqua