来年の県民手帳

タイトルの件，千葉県にしました．

Haruhi-sama gave us a hard problem...

The Haruhi problem is to find the shortest string containing all permutations of $n$ symbols. If $n = 2$, then the Haruhi problem is easy: the shortest string is "121" or "212". However, if $n \geq 3$, then the problem is messy.

See also:
Superpermutation - Wikipedia.