tasks a-s

Task/Non-continuous-subsequences/Haskell/non-continuous-subsequences-1.hs

@@ -0,0 +1,9 @@
+action p x = if p x then succ x else x
+
+fenceM p q s []     = guard (q s) >> return []
+fenceM p q s (x:xs) = do
+  (f,g) <- p
+  ys <- fenceM p q (g s) xs
+  return $ f x ys
+
+ncsubseq = fenceM [((:), action even), (flip const, action odd)] (>= 3) 0

Task/Non-continuous-subsequences/Haskell/non-continuous-subsequences-2.hs

@@ -0,0 +1,4 @@
+continuous = null . dropWhile not . dropWhile id . dropWhile not
+ncs xs = map (map fst . filter snd . zip xs) $
+           filter (not . continuous) $
+             mapM (const [True,False]) xs

Task/Non-continuous-subsequences/Haskell/non-continuous-subsequences-3.hs

@@ -0,0 +1,10 @@
+import Data.List
+
+poset = foldr (\x p -> p ++ map (x:) p) [[]]
+
+ncsubs [] = [[]]
+ncsubs (x:xs) = tail $ nc [x] xs
+  where
+    nc [_] [] = [[]]
+    nc (_:x:xs) [] = nc [x] xs
+    nc  xs (y:ys) = (nc (xs++[y]) ys) ++ map (xs++) (tail $ poset ys)

Task/Non-continuous-subsequences/Haskell/non-continuous-subsequences-4.hs

@@ -0,0 +1,8 @@
+import Data.List (subsequences, tails, delete)
+
+disjoint a = concatMap (cutAt a) [1..length a - 2] where
+	cutAt s n = [a ++ b |	b <- delete [] (subsequences right),
+				a <- init (tails left) ] where
+		(left, _:right) = splitAt n s
+
+main = print $ length $ disjoint [1..20]

Task/Non-continuous-subsequences/Haskell/non-continuous-subsequences-5.hs

@@ -0,0 +1,15 @@
+import Data.List (inits, tails)
+
+subseqs [] = []
+subseqs (x:xs) = [x] : map (x:) s ++ s where s = subseqs xs
+
+consecs x = concatMap (tail.inits) (tails x)
+
+minus [] [] = []
+minus (a:as) bb@(b:bs)
+	| a == b = minus as bs
+	| otherwise = a:minus as bb
+
+disjoint s = (subseqs s) `minus` (consecs s)
+
+main = mapM_ print $ disjoint [1..4]