The domain www.hp.com automatically redirects to your region-specific subfolder based on your IP address. It could also be done using accept-language in htaccess.
So, for instance, if you are located in Germany, hp.com redirects to hp.com/de-de/ via a 301 redirection.
Only the root domain www.hp.com redirects to a region-specific subfolder.
I changed the user-agent of my firefox browser to the Googlebot user agent and visited hp.com while connected from germany, It still redirected to the German subfolder.
So, I guess that when Googlebot visits hp.com it is automatically redirected to hp.com/us-en/ since googlebot has an American IP address.
Then, at the bottom of the HP.com/us-en/ there is a country selector with links to every region-specific hp.com subfolders.
At last, I have checked if it was easy to find hp.com pages on google search. I typed "hp drucker" (hp printer in german) while in the USA. The three first links were from www.hp.com, 1 to the American subfolder /us-en/ and 2 to the german subfolder /de-de/
So, I think this technique works pretty well!
In your case, I would suggest to redirect mysite.hu based on the language of the browser using accept-language in HTACCESS.
So, if someone has a browser with hungarian language in it, this visitor will be redirect to the hungarian subfolder /hu and if the language is english it will be redirected to /en
Googlebot does not have accept-language in his HTTP request, so it will be redirected from mysite.com to mysite.com/hu. It is not a problem for crawling the english version as long as mysite.com/hu is linked to mysite.com/en
#if request to robots.txt no redirection
RewriteCond %{REQUEST_URI} ^robots.txt$
RewriteRule ^ - [L]
#if lang is en then redirect to /en
RewriteCond %{REQUEST_URI} ^/$
RewriteCond %{HTTP:Accept-Language} en [NC]
RewriteRule ^ /en [R=301,L]
#Otherwise redirection from root domain to the default hu
RewriteCond %{REQUEST_URI} ^/$
RewriteRule ^ /hu [R=301,L]