use strict; use warnings; 
use Data::Dumper; 
no warnings 'once' ; 
  local $Data::Dumper::Sortkeys=1;
  local $Data::Dumper::Indent=1; 
use warnings; 
my $c={}; 
$c->{'1top'}={name=>'1top',childs=>[],parent=>undef}; 
makechild(name=>'child1',parent=>'1top'); 
makechild(name=>'child2',parent=>'1top'); 
makechild(name=>'child21',parent=>'child2'); 
makechild(name=>'child22',parent=>'child2'); 

print Dumper($c);


sub makechild{ 
  my %args=@_; 
  my $node={}; 
  $c->{$args{name}}=$node;
  $node->{name}=$args{name}; 
  $node->{childs}=[];
  my $parent=$c->{$args{parent}};  
  $node->{parent}=$parent;
  push @{$parent->{childs}},$node;
}