Project Euler 解答

Project Euler Problem 086

Project Euler Problem 086

import Data.List

-- 平方数かの判定
isq :: Integral a => a -> Bool
isq n = n == r*r where r = floor $ sqrt $ fromIntegral n

ans1 :: Maybe Int
ans1 = findIndex (>(10^6)) $ scanl1(+) $ map r [0..] where
  r m= sum[a`quot`2 - if a>m then a-m-1 else 0 | a<-[1..m+m],isq (a*a+m*m)]

--Just 1818
main = print ans1

since 2013