소인수분해정보로 최대공약수찾기 (하스켈)

big-gcd.hs

import Data.List
import Data.Function

type Fac = [(Int, Int)]

list2tuples :: [Int] -> Fac
list2tuples [] = []
list2tuples (a:b:xs) = (a,b):(list2tuples xs)
list2tuples _  = error "Error"

tuples2list = concatMap (\(a, b) -> [a, b])


myGCD :: Fac -> Fac -> Fac
myGCD xs ys = zip cs es
  where
  cs = (intersect `on` map fst) xs ys
  findE c = snd . head . dropWhile ((/= c) . fst)
  findMinE c = (min `on` findE c) xs ys
  es = map findMinE cs  

solve = do
  getLine
  inputData <- (map (map read . words) . lines) <$> getContents
  let result = tuples2list . folr1 myGCD . map list2tuples $ inputData
  putStrLn . unwords . map show $ result

main = solve