use strict;
use warnings;
use Carp;
use List::Util 'max';

my @factors = ('B,B,D,D,E,E' x 10) x 10_000;
my @numbers = ('80,25,30,1000,45,0.5' x 10) x 10_000;

my $search  = 'BDE';

for my $i ( 0 .. $#factors ) {
    print_groups(
        group( $factors[$i], $numbers[$i], $search )
    );
}

sub group {
    my ( $factors, $numbers, $search ) = @_;

    my @factors = split ',', $factors;
    my @numbers = split ',', $numbers;

    croak "Fatal error!"
      unless @factors == @numbers;

    my @groups;

    for my $s (split '', $search) {
        my @temp = ($s);
        for my $i ( 0 .. $#factors ) {
            push @temp, $numbers[$i] if $factors[$i] eq $s;
        }
        push @groups, \@temp;
    }

    return \@groups;
}

sub print_groups {
    my $groups  = shift;
    my $current = shift || 0; # or defined-or
    my $prev    = shift;

    if ( not defined $groups->[$current] ) {
        print $prev , "\n";
        return;
    }

    my ( $factor, @numbers ) = @{ $groups->[$current] };

    my $max = max map length, @numbers;

    for my $number (@numbers) {
        print_groups(
            $groups,
            $current + 1,
            ( $prev ? "$prev " : '' )
            . ( sprintf '%s = %-*s', $factor, $max, $number )
        );
    }
}