What should I do when I come home at night and meet a punk?

Call the police first and tell the police the specific situation. The police will step up patrols in that area.

Secondly, you can choose to live on campus (we all live here). If you can't live on campus, try to go with your classmates instead of going alone. You'd better tell your family if you can get it at home.

Furthermore, when walking (especially at night), try not to drill in places with few pedestrians, and pay attention to safety.