Lists all columns that have the highest in the event of a tie (e.g. id004;10;30;30)

use strict;
use warnings;
use feature qw( say );

use List::Util qw( max );

<>;
while (<>) {
   chomp;
   my @fields = split /;/;
   my %indexes;
   push @{ $indexes{ $fields[$_] } }, $_ for 1..$#fields;
   say join ",", @{ $indexes{ max keys %indexes } };
}
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As a "one liner":

perl -MList::Util=max -F\; -lanE'
   BEGIN { <> }
   my %indexes;
   push @{ $indexes{ $F[$_] } }, $_ for 1..$#F;
   say join ",", @{ $indexes{ max keys %indexes } };
'
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