Extract unique subdirectories from a file, ignoring parent dirs

dirsunique.pl

#!/usr/bin/perl
# pgregg@pgregg.com
use Data::Dumper;
my $d={};
while(<STDIN>) {
  chomp;
  next if(/^$/);
  @bits = split(/\//, $_);
  $last = pop(@bits);
  $dr = $d;
  for my $bit (@bits) {
    next if ($bit eq "");
    if (exists $dr->{$bit}) {
      if (ref $dr->{$bit} ne HASH) {
        #print "deleting $bit\n";
        delete $dr->{$bit};
        #print "reinit $bit\n";
        $dr->{$bit} = {};
      } else {
        #print "ignoring $bit\n";
      }
    } else {
      #print "init $bit\n";
      $dr->{$bit} = {};
    }
    #print "moving ptr\n";
    $dr = $dr->{$bit};
  }
  if (!exists $dr->{$last}) {
    $dr->{$last} = 1;
  }
}
print Dumper($d);

sub walkhashref {
  my $arg = shift;
  my $prefix = shift;
  my $line;
  foreach $k (keys %{$arg}) {
    $line = $prefix . "/$k";
    if (ref $arg->{$k} eq HASH) {
      walkhashref($arg->{$k}, $line);
    } else {
      print $line . "\n";
    }
  }
}

walkhashref($d, "");

Sample Input:
/a
/a/b/
/a/b/c
/g/
/g/h
/x/y/z/foo
/x/y/bar
/x/y
/a

Output:

$ ./dirunique2.pl < dirs.txt

$VAR1 = {

'a' => {

'b' => {

'c' => 1

}

},

'g' => {

'h' => 1

},

'x' => {

'y' => {

'bar' => 1,

'z' => {

'foo' => 1

}

}

}

};

/a/b/c

/g/h

/x/y/bar

/x/y/z/foo