I'm male. Imagine I arrive at a youth hostel where I'm the only Jew. There's a male-only dorm room; down the hallway, there's also a female-only dorm room. Assume that all the doors are unlocked. Do the laws of yichud allow me to sleep in the male-only dorm room?
Rabbi N.D. Dubov cites the Minchas Ish and says that the hallways of a hotel are public domains. So perhaps the hallways of a youth hostel are also public domains.
But perhaps I'm wrong, or perhaps there may be other halachic problems with sleeping in a non-Jewish youth hostel. I'm not a rabbi. CYLOR.
 In chapter 6 note 235 of the free online version of The Laws of Yichud.