ProjectEuler/haskell/src/0027.hs

import Utils

import Data.List
import Data.Maybe

--import Debug.Trace
--import Text.Printf

numOfPrimes :: Int -> Int -> Int
numOfPrimes a b = go' 0
  where
    go' :: Int -> Int
    go' n
      -- | trace (printf "go' n=%-5d r=%-5d" n r) False = undefined
      | otherwise = if (isPrime r) then go' (n+1) else n
      where r = (n*n) + (a*n) + b

solution :: Int
solution = combinations2 [aDLimit..aULimit] [bDLimit..bULimit]
             |> mapFindMaxInitial (uncurry numOfPrimes)
             |> (uncurry (*))
  where
    aULimit = 999
    bULimit = 1000
    aDLimit = -999
    bDLimit = -1000

main :: IO ()
main = putStrLn ("Solution: " ++ show solution)