This code does a width first traversal without recursion and returns some results you may find easier to work with. All it does is iterate over a list of dirs. Starting at the root dir it just keeps pushing the subdirs it finds onto the end of this list, thus the width first traversal.

# recurses the directory tree with the root as the arg
# returns paths relative to root -> not absolute paths
# does not return root dir itself in @dirs list
# returns references \@dirs and \@files and \%tree

sub recurse_tree {
    my $root = shift;
    my @dirs = ( $root );
    my @files;
    my %tree;
    for my $dir ( @dirs ) {
        opendir DIR, $dir or die("Can't open $dir\n"); # could just ne
+xt
        (my $rel_dir = $dir) =~ s!^\Q$root\E/?!!;
        while ( my $file = readdir DIR ) {
          next if $file eq '.' or $file eq '..';
          next if $file =~ m/^_/;  # skip _ prefix files and dirs
          next if -l "$dir/$file"; # don't follow sym links
            push @dirs, "$dir/$file" if -d "$dir/$file";
            push @files, "$dir/$file" if -f "$dir/$file";
            push @{$tree{$rel_dir}}, $file if -f "$dir/$file" and $fil
+e =~ m/\.html?$/;
        }
        closedir DIR;
    }
    # make paths relative to $root, comment out for full path
    @dirs = grep { $_ and ! m!^/$! } map{ s!^\Q$root\E/?!!; $_ } @dirs
+;
    @files = map{ s!^\Q$root\E/?!!; $_ } @files;
  return \@dirs, \@files, \%tree;
}
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