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

24 lines
763 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