天下一なんちゃらの例題を解いてみたよ

Haskell

http://www.klab.jp/tenka1programer/bosyu.html
ここを見て，

import Data.Char
import Data.Bits
fromhexchar x | isDigit x = (ord x) - (ord '0')
              | True = (ord (toLower x)) - (ord 'a') + 10 
fromhexstr (x:y:xs) = ((fromhexchar x) * 16 + (fromhexchar y)):(fromhexstr xs)
fromhexstr [] = []
utf8len (x:y:z:xs) | x < 128   = 1 + utf8len (y:z:xs)
                   | x < 196   = 1 + utf8len (z:xs)
                   | otherwise = 1 + utf8len xs
utf8len [] = 0
main = getContents >>= print.utf8len.fromhexstr.(filter (not.isSpace))

こんなのを書いて，
http://www16.atwiki.jp/tokoroten/pages/1153.html
ここを見て，

import Data.Char
utf8len (x:xs) | (x == 'f' || x == 'e') = 1 + utf8len (drop 5 xs)
               | (x == 'd' || x == 'c') = 1 + utf8len (drop 3 xs)
               | otherwise              = 1 + utf8len (tail xs)
utf8len [] = 0
main = getContents >>= print.utf8len.(filter (not.isSpace))

こんなのを書いた．

$ echo e4bba5e4b88be381aee69687e5ad97e58897e381af5554462d\
  38e38292e69687e5ad97e382a8e383b3e382b3e383bce38387e382a\
  3e383b3e382b0e5bda2e5bc8fe381a8e38199e3828b3136e980b2e69\
  5b0e381aee38390e382a4e38388e58897e381a7e38182e3828be380\
  82 | runhaskell ./tenka2.hs
41

うん．久々のHaskellで鈍ってるかなぁーって思ったんだけど，鈍ってたのはHaskellの腕じゃなくて，問題をシンプルに解く発想力のほうだった．

おわり