belyaev-mikhail

newtype PSet a = PSet{ contains :: (a -> Bool) }
newtype PSet2 a = PSet2{ contains2 :: (a -> Bool) }
newtype PSet3 a = PSet3{ contains3 :: (a -> Bool) }

-- сложение множеств
instance Monoid (PSet a) where
  mempty = PSet (\a -> False)
  mappend (PSet f1) (PSet f2) = PSet (\a -> (f1 a) || (f2 a))

-- пересечение множеств

belyaev-mikhail

data ReverseList a = RNil | RCons (ReverseList a) a


showAsList :: (Show a) => ReverseList a -> String
showAsList RNil = ""
showAsList (RCons RNil h) = show h
showAsList (RCons tl hl) = (showAsList tl) ++ ", " ++ (show hl)


toList :: ReverseList a -> [a]

belyaev-mikhail

data PeanoNumber = Zero | Succ (PeanoNumber) | Pred (PeanoNumber) deriving Show


isSimple :: PeanoNumber -> Bool
isSimple Zero = True
isSimple (Succ (Pred _)) = False
isSimple (Pred (Succ _)) = True
isSimple (Succ num) = isSimple num
isSimple (Pred num) = isSimple num

belyaev-mikhail

my_foldr :: (a -> b -> b) -> b -> [a] -> b
my_foldr f x [] = x
my_foldr f x (h : t) = f h (my_foldr f x t)

my_foldl :: (b -> a -> b) -> b -> [a] -> b
my_foldl f x [] = x
my_foldl f x (h : t) = my_foldl f (f x h) t

my_map :: (a -> b) -> [a] -> [b]
my_map _ [] = []

belyaev-mikhail

data BinaryTree = EmptyTree
									| Leaf Integer
									| Node Integer BinaryTree BinaryTree

hasLeft :: BinaryTree -> Bool
hasLeft (EmptyTree) = False
hasLeft (Leaf _) = False
hasLeft (Node _ EmptyTree _) = False
hasLeft (Node _ _ _) = True

belyaev-mikhail

1 вариант

Problem 1

Дан список и два числа: m и n (0 < m < 1000). Необходимо заменить все элементы списка с индексами, кратными m, на n.

Пример:

changeEls [1, 2, 3, 4, 5] 2 7
> [7, 2, 7, 4, 7]