Create sorted_digits.hs

sorted_digits.hs

@@ -0,0 +1,18 @@
+import Data.List
+
+digits :: Int -> [Int]
+digits n = unfoldr nextDigit n where
+  nextDigit 0 = Nothing
+  nextDigit c = Just $ (c `mod` 10, c `div` 10)
+
+isSorted :: Int -> Bool
+isSorted n = (all (uncurry (<=)) ds') || (all (uncurry (>=)) ds'') 
+  where ds = digits n
+        ds' = zip ds (maxBound : ds)
+        ds'' = zip ds (minBound : ds)
+
+main = do
+  print $ isSorted 123456
+  print $ isSorted 1234561
+  print $ isSorted 97541
+  print $ isSorted 99431