my @max;
for (my $n = 0; $n < @lines; $n++) {  # Assume the rows are in @lines
    $values[$n] = [split /;/, $lines[$n]];
    shift @values;
    for (my $i = 0; $i < @{$values[0]}; $i++) {
        if ($values[$i] >= $lines[$max[$i]||0][$i]) {
            $max[$i] = $n;
        }
    }
}
print "$_\n" for @max;
[download]

  DB<109> $txt='id003;30;80;10'
 
  DB<110> local $.=0; @sort = sort {$a->[0] <=> $b->[0]} map { [$_ => 
+$.++] } split /;/, $txt 
 
  DB<111> print $sort[-1]->[1]
2
[download]

Was to lazy to eliminate the id field first. :)

This code may give idea to you

my @a = (1,23,451,289,5);
my @b = (341,561,5,67,78,891);
&func( \@a);
&func (\@b);

sub func(){
    my @myarray = @{$_[0]};
    my $max;
    my $index;
    my $x = 0;
    for ( @myarray )
    {
            if (!defined $max or $_ > $max ){
            $index = $x ; 
            $max = $_;
            }
        $x++;
    }
    print "The greatest is element number $index: $myarray[$index]\n";

}
[download]

Output

The greatest is element number 2: 451

The greatest is element number 5: 891

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 } };
}
[download]

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 } };
'
[download]

• For each line in the input,
  • Split the line into its pieces, separating the row ID from the data,
  • Assume the first is the biggest,
  • Walk down the indices, keeping track of which represents the largest, and
  • Report that answer

foreach my $l (@line) {
  my ($row_id, @row_data) = split( /;/, $l ) ;
  my $idx = 0 ;
  do { $idx = $_ if $row[$_] > $row[$idx] } for 1..$#row_data ;
  print (1+$idx), "\n" ;
}
[download]

Looks like that data is CSV (with a M$ sep_char). You could/should switch to a real CSV reader when the data is actually more complicated than your example snippet. The de-facto modules to parse CSV are Text::CSV_XS and Text::CSV. If the data is more complicated, you could also turn to using DBD::CSV and hit the data with SQL statements.

#!/usr/bin/perl -w
use strict;
use List::Util qw(reduce);

while (<DATA>)
{
   chomp;
   my (@array) = split';',$_;
   
   my $ColumnNumber = 
      reduce { $array[$a] >= $array[$b] ? $a : $b } 1..@array-1; 
      
   print $ColumnNumber, "\n";  
}

=prints
3
3
2
=cut

__DATA__
id001;10;10;30
id002;30;20;50
id003;30;80;10
[download]

use strict;
use warnings;

my $header = <DATA>;
while (my $line = <DATA> )
{
    chomp $line;
    my @array = split /;/, $line, -1;
    my $row_id = shift @array; 
    my @sorted = sort {$b<=>$a} @array;
    my $max = shift @sorted;
    my @index = map {$_ + 1} grep { $array[$_] eq $max } 0..$#array;
    print "Max value in the row $row_id is $max ";
    print "in the column(s) ",  @index > 1 ? join ',', @index : @index
+, ".\n";
}

__DATA__
row_id;value1;value2;value3
id001;10;10;30
id002;30;20;50
id003;30;80;10
id004;30;90;90
id005;50;50;10
[download]

Max value in the row id001 is 30 in the column(s) 3.
Max value in the row id002 is 50 in the column(s) 3.
Max value in the row id003 is 80 in the column(s) 2.
Max value in the row id004 is 90 in the column(s) 2,3.
Max value in the row id005 is 50 in the column(s) 1,2.
[download]