Efficient Linked Lists

[Ionizor]

I'm trying to create a pair of hashes so that I can easily traverse a list of filenames in either direction. The code I've come up with follows. Does anybody know a more efficient way to do this? Preferably so that I can remove the ugly "do first case, loop by index, do last case" thing I've got. I'd prefer one loop but didn't want to put a pair of ifs inside that will only be used once each.

# populate filename array
my @filenames = qw(file1 file2 file3 file4 file5 file6);

my %next;
my %prev;

# Link next to first filename
$next{$filenames[0]} = $filenames[1];

# Link next and prev to all the filenames
for (my $fileindex = 1; $fileindex < scalar (@filenames) - 1; $fileind
+ex++) {
  $next{$filenames[$fileindex]} = $filenames[$fileindex + 1];
  $prev{$filenames[$fileindex]} = $filenames[$fileindex - 1];
}

# Link prev to last filename
$prev{$filenames[-1]} = $filenames[-2];

Thanks, monks.

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