CoinSolver.hs

   1 import Data.Map.Strict as M
   2 import Data.Map.Strict ((!))
   3 import Data.List
   4
   5 data Coins = Red | Blue | Shiny | Corroded | Concave
   6   deriving (Ord, Eq, Show, Enum, Bounded)
   7
   8 allCoins = [Red .. Concave]
   9
  10 main = print solve
  11
  12 coins :: M.Map Coins Int
  13 coins = M.fromList $ zip [Red .. Concave] [2, 9, 5, 3, 7]
  14
  15 solve :: [[Coins]]
  16 solve = [ [a, b, c, d, e]
  17         | [a, b, c, d, e] <- permutations allCoins
  18         , (coins ! a) + (coins ! b) * (coins ! c) ^2 + (coins ! d) ^3 - (coins ! e) == 399
  19         ]