Re: Sorting by association, a tail of dependency resolving gone nowhere

Sounds like Re: Problems with sorting (recommending Sort::Topological) might be of help.

If you'd rather roll your own, I thought this solution was rather elegant:

my %dmap = (
1        => undef,
2        => 4,
3        => 5,
4        => 3,
5        => 1,
);

my @sorted;
my %sorted_contents;
my %tried;

sub insert {
  my $candidate = $_[0];
  return if exists $sorted_contents{$candidate};
  die "Cycle!\n" if $tried{$candidate}++;
  my $dependency = $dmap{$candidate};
  insert($dependency) if (defined $dependency);
  $sorted_contents{$candidate} = push @sorted, $candidate;
}

insert $_ for keys %dmap;

print "@sorted\n";
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Caution: Contents may have been coded under pressure.

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