pizza.hs

import Data.List
import Data.Maybe
import Data.Ord

shareArea = 85
pizzaArea size = pi * (size/2)^2
totalPizzaArea = sum . map pizzaArea

sufficient area sizes | area < 0 = [[]]
sufficient area [] = []
sufficient area (size:sizes)
	=  map (size:) (sufficient (area - pizzaArea size) (size:sizes))
	++ sufficient area sizes

-- chooseSmallestArea = minimumBy (comparing totalPizzaArea)
chooseCheapest prices = minimumBy (comparing (sum . map (fromJust . flip lookup prices)))

makeOrder shares prices = chooseCheapest prices (sufficient (shareArea*shares) (map fst prices))