more Data::Dumper trickery plus a more complicated input like demonstrated by TheDamian.

output: 

  Professor  
    Amy  
    Cubert  
    Hermes  
      Dwight  
      Leela  
        Bender  
        Fry  
      Zoidberg  
  Satan  
    Beelzebub  
      Lucky  
    Damien  
  'Satan Jr'  
    Emacs  
      LanX

[download]

use strict;
use warnings;
use Data::Dumper qw/Dumper/;
use Data::Dump qw/pp/;

#pp
my $input = get_input();

my ( $tree, @roots );

while ( my ( $top, $second ) = each %$input ) {

    while ( my ( $id, $attr ) = each %$second ) {

        my $boss_id = $attr->{boss};
        my $name    = $attr->{name};

        unless ($boss_id) {
            push @roots, $name;
            next;
        }

        my $boss_name = $second->{$boss_id}->{name};

        $tree->{$boss_name}{$name} = $tree->{$name} //= {};
    }
}

$Data::Dumper::Indent = 1;
$Data::Dumper::Terse  = 1;
#$Data::Dumper::Pad      = '#';
$Data::Dumper::Quotekeys = 0;
#$Data::Dumper::Pair     = "";
$Data::Dumper::Sortkeys = 1;

my $graph = Dumper {
    map { $_ => $tree->{$_} } @roots
};

$graph =~ s/[{},=>]//g;    # delete hash symbols
$graph =~ s/^\s*\n//gm;    # delete empty lines

print $graph;

sub get_input {
    return {
        666 => {
            1   => { boss => 666, name => "Beelzebub" },
            11  => { boss => 245, name => "LanX" },
            99  => { boss => 666, name => "Damien" },
            245 => { boss => 333, name => "Emacs" },
            333 => { boss => 0,   name => "Satan Jr" },
            666 => { boss => 0,   name => "Satan" },
            777 => { boss => 1,   name => "Lucky" },
        },
        1929 => {
            1    => { boss => 1929, name => "Hermes" },
            2    => { boss => 1,    name => "Leela" },
            3    => { boss => 1929, name => "Amy" },
            4    => { boss => 1,    name => "Zoidberg" },
            480  => { boss => 2,    name => "Fry" },
            1919 => { boss => 2,    name => "Bender" },
            1929 => { boss => 0,    name => "Professor" },
            3968 => { boss => 1929, name => "Cubert" },
            4425 => { boss => 1,    name => "Dwight" },
        },
    };
}

[download]

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

In reply to Re^2: out of order tree generation (Data::Dumper) by LanX
in thread out of order tree generation by adambot

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