Problem 71

71.hs

@@ -0,0 +1,9 @@
+import Data.Ratio
+
+closer :: Rational -> Rational -> Rational
+closer curr prev = let goal = (3 % 7) in if curr < goal && (goal - curr) < (goal - prev) then curr else prev
+
+closest :: Integer -> Rational
+closest bound = foldr closer 0 $ map (\d -> let n = floor (d * 3 % 7) in (n % d)) [8..bound]
+
+main = print $ closest 1000000