Sum multiples of 3 and 5: Difference between revisions

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 <lang haskell>import Data.List (nub)
+sum35 :: Integral a => a -> a
-sumMul n f = f * n1 * (n1 + 1) `div` 2 where n1 = (n - 1) `div` f
 sum35 n = sumMul n 3 + sumMul n 5 - sumMul n 15
+sumMul :: Integral a => a -> a -> a
--- below are for variable length inputs
+sumMul n f = f * n1 * (n1 + 1) `div` 2
+  where
+    n1 = (n - 1) `div` f
+-- Functions below are for variable length inputs
+pairLCM :: Integral a => [a] -> [a]
 pairLCM [] = []
-pairLCM (x:xs) = map (lcm x) xs ++ pairLCM xs
+pairLCM (x:xs) = (lcm x <$> xs) ++ pairLCM xs
+sumMulS :: Integral a => a -> [a] -> a
 sumMulS _ [] = 0
-sumMulS n s = sum (map (sumMul n) ss) - sumMulS n (pairLCM ss)
+sumMulS n s = sum (sumMul n <$> ss) - sumMulS n (pairLCM ss)
-    where ss = nub s
+  where
+    ss = nub s
-main = do
+main :: IO ()
+main =
-    print $ sum35 1000
+  mapM_
-    print $ sum35 100000000000000000000000000000000
-    print $ sumMulS 1000 [3,5]
+    print
+    [ sum35 1000
-    print $ sumMulS 10000000 [2,3,5,7,11,13]</lang>
+    , sum35 100000000000000000000000000000000
+    , sumMulS 1000 [3, 5]
+    , sumMulS 10000000 [2, 3, 5, 7, 11, 13]
+    ]</lang>
 {{out}}
 <pre>233168