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  1. import Control.Monad
  2.  
  3. isSquare a b = rem < 0.00000001
  4.   where (int, rem) = properFraction $ sqrt $ fromIntegral $ a + b :: (Int, Double)
  5.  
  6. task nums = do
  7.   let
  8.     go prev nums = do
  9.       a <- nums
  10.       guard $ isSquare prev a
  11.       case filter (/=a) nums of
  12.         [] -> return [a]
  13.         nums1 -> do
  14.           as <- go a nums1
  15.           return $ a : as
  16.   a <- nums
  17.   go a (filter (/=a) nums)
  18.  
  19.  
  20.  
  21. main = print $ task [1..17]
  22.  
Success #stdin #stdout 0s 4704KB
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Standard input is empty
stdout
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[[9,7,2,14,11,5,4,12,13,3,6,10,15,1,8,17],[8,1,15,10,6,3,13,12,4,5,11,14,2,7,9,16]]
https://ideone.com/Ivmnyj
language:
Haskell (ghc 8.4.4)
created:
8 years ago
visibility:
public

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