rpi.hs

import qualified Data.ByteString.Char8 as B
import qualified Data.MemoCombinators as Memo

findRPI :: Int -> [B.ByteString] -> String
findRPI games matches = unlines $ map (\t -> show $ rpi t matches) [0..(games-1)]

rpi :: Int -> [B.ByteString] -> Double
rpi team matches = 0.25 * wp' + 0.50 * owp' team matches + 0.25 * oowp' team matches
  where wp'   = wp (matches !! team) Nothing
        owp'  = Memo.integral owp
        oowp' = Memo.integral oowp

wp :: B.ByteString -> Maybe Int -> Double
wp matches exclude = fromIntegral won/fromIntegral total
    where games    = B.filter (/= '.') matches'
          total    = B.length games
          won      = (B.length . B.filter (=='1')) games
          matches' = case exclude of
                          Nothing -> matches
                          Just t  -> B.take t matches `B.append` B.drop (t+1) matches

owp :: Int -> [B.ByteString] -> Double
owp team matches = sum owps/nOpponents
    where opponents = map fst $ filter (\e -> snd e /= '.') $ zip [0..] (B.unpack $ matches !! team)
          nOpponents = (fromIntegral . length) opponents
          owps       = map (flip wp (Just team) . (\ i -> matches !! i)) opponents

oowp :: Int -> [B.ByteString] -> Double
oowp team matches = sum oowps/nOpponents
    where opponents = map fst $ filter (\e -> snd e /= '.') $ zip [0..] (B.unpack $ matches !! team)
          nOpponents = (fromIntegral . length) opponents
          oowps       = map (`owp` matches) opponents

printCase n = do
    nGames <- fmap read getLine
    ts <- mapM (\_ -> fmap B.pack getLine) [1..nGames]
    putStr $ "Case #" ++ show n ++ ":\n" ++ findRPI nGames ts

main = do
    t <- fmap read getLine
    mapM_ printCase [1..t]