#!perl
use strict;
use warnings;
use File::Path qw(make_path);

# Parent structure directory.
my @structs = (
  dir_tree( 'struct', 7, 1, 2),
);

# Subfolder molecule directory.
my @molecs = (
  [dir_tree( 'AB', 6, 1, 3 )], # note []
  [dir_tree( 'BC', 6, 1, 3 )],
);

# Subfolder steps directory.
my @steps = dir_tree( 'S', 6, 1, 2 );

for my $structs (@structs) {
  #mkdir "/media/RAIDstorage/home/results/$structs";
  print "/media/RAIDstorage/home/results/$structs";
  print "\n";

  my $ar = shift @molecs;
  for my $molecs (@$ar) {
    for my $steps (@steps) {
      #make_path "/media/RAIDstorage/home/results/$structs/$molecs/$steps";
      print "/media/RAIDstorage/home/results/$structs/$molecs/$steps";
      print "\n";
    } 
  }
}

# Define subroutine here.
sub dir_tree {
  my ( $name, $total_length, $from, $to ) = @_;

  my $length = $total_length - length($name);
  my $format = "${name}%0${length}d";
  return map sprintf( $format, $_ ), $from .. $to;
}