kann angenommen werden= can be supposed, assumed

and this only for a very complex "average case"! So without references it's hearsay.

Anyway it's certainly not O(1), which (AGAIN) means fixed complexity, no matter how big n gets. And this algo isn't even stable and can go havoc up to O(n).

Your playing around with a "hammer" of other peoples toolbox, take their advice and better don't touch ... you might hurt yourself.

UPDATE: Palavra, palavra, palavra - Turkish 8)