RosettaCodeData/Task/Knapsack-problem-Continuous/Haskell/knapsack-problem-continuous...

27 lines
689 B
Haskell

import Data.List (sortBy)
import Data.Ord (comparing)
import Text.Printf (printf)
-- (name, (value, weight))
items =
[ ("beef", (36, 3.8))
, ("pork", (43, 5.4))
, ("ham", (90, 3.6))
, ("greaves", (45, 2.4))
, ("flitch", (30, 4.0))
, ("brawn", (56, 2.5))
, ("welt", (67, 3.7))
, ("salami", (95, 3.0))
, ("sausage", (98, 5.9))
]
unitWeight (_, (val, weight)) = fromIntegral val / weight
solution k = loop k . sortBy (flip $ comparing unitWeight)
where
loop k ((name, (_, weight)):xs)
| weight < k = putStrLn ("Take all the " ++ name) >> loop (k - weight) xs
| otherwise = printf "Take %.2f kg of the %s\n" (k :: Float) name
main = solution 15 items