From a9ee47b61558efe09aee23f5671aabd0c3747e8a Mon Sep 17 00:00:00 2001 From: Joe Zhao Date: Tue, 17 Mar 2015 11:05:29 +0800 Subject: p -> h --- h10.hs | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) create mode 100644 h10.hs (limited to 'h10.hs') diff --git a/h10.hs b/h10.hs new file mode 100644 index 0000000..68ffade --- /dev/null +++ b/h10.hs @@ -0,0 +1,20 @@ +import Control.Applicative +import Control.Arrow +import Data.List + +encode :: Eq a => [a] -> [(a,Int)] +encode = foldr elim [] + where + elim e [] = [(e,1)] + elim e p@(n:ns) + | e == fst n = (e,1 + (snd n)):ns + | otherwise = (e,1):p + +encode' (x:xs) = let (first,rest) = span (==x) xs + in (x,1+(length first)) : encode' rest + +encode' [] = [] + +encode'' xs = map (head &&& length) $ group xs + +encode''' xs = map ((,) <$> head <*> length) $ group xs -- cgit v1.2.3-70-g09d2