Submission #169625

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Source Code Expand

import Data.List
main = getContents >>= print . solve . tail . map (read :: String -> Integer) . lines

fact :: [Double]
fact = [1,1,2,6,24,120,720,5040,40320]

solve :: [Integer] -> Double
solve xs = if length xs > 8 then 0
           else (/(fact!!(length xs))) $ fromIntegral $ foldr (\ps acc -> calc ps 0 + acc) 0 $ permutations xs

calc :: [Integer] -> Integer -> Integer
calc [] acc = acc
calc (x:xs) acc = calc (sub x xs) (acc + (if x > 0 then 1 else 0))
  where
    sub y [] = []
    sub y (z:zs) = if z `mod` y == 0 then (-z):sub y zs
                   else z:sub y zs

Submission Info

Judge Result