Here is a list of 30 English nouns in their singular and plural form. Your job is simply to write the shortest regular expression that matches all the nouns in one form and none in the other (easy, all English nouns end in
s in plural form right?).
SINGULAR PLURAL --------- -------- car cars boat boats man men woman women omen omens bus buses cactus cacti spy spies pie pies louse lice mouse mice amice amices goose geese creese creeses person people child children siren sirens ox oxen foot feet tooth teeth formula formulae minx minxes sphinx sphinges wife wives knife knives ion ions criterion criteria jinni jinn zero zeros hero heroes
Yes, some of the words have alternative forms, but these are the ones we're going to use.
Here is a script that can help you with the testing; just put your regex between the two slashes (
/) on the first line.