HaskellでDP(2)

import Control.Monad.State (State,get,put,evalState)
import Control.Monad
import Prelude hiding(lookup)
import Data.Map (Map,lookup,insert,empty)
import IO
import System
import Data.List(sortBy)
-- ====動的計画法====
type Table k v = Map k v
type Memo a b = State (Table a b) b
type Capacity = Int
type Item = (Int,Int)
-- メモ化のテクニック
memoise :: Ord a => (a -> Memo a b) -> a -> Memo a b
memoise f x = do
table <- get
case (lookup x table) of
Just y -> return y
Nothing -> do fx <- f x
table' <- get
put(insert x fx table')
return fx
runM :: (a -> Memo a b) -> a -> b
runM m v = evalState (m v) empty
-- 動的計画法本体
knap_dp ::(Capacity,[Item]) -> Memo (Capacity,[Item]) Int
knap_dp (,_)= return 
knap_dp (b,[])
| b <  = return $ -1
| otherwise = return 
knap_dp (b,i:is)
| b <  = return $ -1
| otherwise = memoise knap_dp' (b,i:is)
where
knap_dp' (b,i:is) =
do x <- knap_dp(b,is)
y <- knap_dp(b- snd i,is)
return $ if y <  then x  else max x $ y+fst i
run_dp = runM knap_dp
-- ====分枝限定法====
itemSort = sortBy g
where g (a,b) (c,d)
| a*d - b*c ==  =EQ
| a*d - b*c >  =LT
| otherwise = GT
-- 連続緩和問題を貪欲法で解く
relax ::(Capacity,[Item])->Int
relax (c,is) = relax' (c,itemSort is)
relax' ::(Capacity,[Item])->Int
relax'(_,[])=
relax'(c,i:is)
| c < snd i = fst i * c `div` snd i
| otherwise = relax'(c-snd i,is) + fst i
-- 分枝限定法本体
knap_bb ::(Capacity,[Item])->Int->Int->Int
knap_bb (c,[]) v s
| c <  = s
| otherwise = v
knap_bb (c,i:is) v s
| ((+v) $! relax' (c,i:is)) <= s = s
| c <  = s
| otherwise = let !s1 =knap_bb(c-snd i,is) (v+ fst i) s
!s2 =knap_bb(c,is) v s1
in max s1 s2
run_bb (c,is) = knap_bb (c,itemSort is')  v
where is' = filter ((<=c).snd) is
v = foldl1 max . map fst $ is'
-- テストデータ
items ::[Item]
items =[(10,2),(6,19),(29,13),(12,7)]
-- 入出力
getInts = liftM (map read .words) getLine :: IO [Int]
getItem = liftM (toTuple . tail . map read . words) getLine :: IO Item
where toTuple (x:y:zs) = (x,y)
main :: IO ()
main = do
arg <- getArgs
[num,capacity] <- getInts
items <- replicateM num getItem
case head arg of
"bb" -> putStrLn.show $ run_bb (capacity,items)
"dp" -> putStrLn.show $ run_dp (capacity,items)
_  -> putStrLn "I need algorithm type"