From 63acd97fb088da2ae5aee5d36460ee30e3bbeabb Mon Sep 17 00:00:00 2001 From: Joe Zhao Date: Mon, 16 Mar 2015 15:42:57 +0800 Subject: +10 --- p10.hs | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) create mode 100644 p10.hs diff --git a/p10.hs b/p10.hs new file mode 100644 index 0000000..68ffade --- /dev/null +++ b/p10.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