- Plain Strings (207):
foo
- Anchors (208):
k$
- Ranges (202):
^[a-f]*$
- Backrefs (201):
(...).*\1
- Abba (169):
^(.(?!(ll|ss|mm|rr|tt|ff|cc|bb)))*$|^n|ef
- A man, a plan (177):
^(.)[^p].*\1$
- Prime (286):
^(?!(..+)\1+$)
- Four (199):
(.)(.\1){3}
- Order (198):
^[^o].....?$
- Triples (507):
(^39|^44)|(^([0369]|([147][0369]*[258])|(([258]|[147][0369]*[147])([0369]*|[258][0369]*[147])([147]|[258][0369]*[258])))*$)