Ninety-Nine Haskell Problems: #5

-- H-99: Ninety-Nine Haskell Problems: Problem 5: Reverse a list.

import Data.List (sortOn)

e1 :: String
e1 = "A man, a plan, a canal, panama!"

e2 :: [Int]
e2 = [1,2,3,4]

e3 :: [()]
e3 = []

main :: IO ()
main = do
  printTestList [e1]
  printTestList [e2]
  printTestList [e3]

printTestList :: Show a => [[a]] -> IO ()
printTestList list = mapM_ print
  $ zip ([1 .. ] :: [Int])
  $ functionsList <*> list

functionsList :: [[a] -> [a]]
functionsList = [one, two, three, four, five, six, seven, eight, nine, ten, eleven]

one :: [a] -> [a]
one = reverse

two :: [a] -> [a]
two [] = []
two (x:xs) = two xs ++ [x]

three :: [a] -> [a]
three [] = []
three list = three (tail list) ++ [head list]

four :: [a] -> [a]
four = foldl (flip (:)) []

five :: [a] -> [a]
five [] = []
five list = last list : five (init list)

six :: [a] -> [a]
six list = aux (length list - 1) list
  where
    aux _ [] = []
    aux index lst = drop index lst ++ aux (index - 1) (take index lst)

seven :: [a] -> [a]
seven [] = []
seven list = aux list (length list - 1)
  where
    aux lst 0 = [head lst]
    aux lst index = lst !! index : aux lst (index - 1)

eight :: [a] -> [a]
eight list = map snd
  $ sortOn fst
  $ zip [(length list - 1), (length list - 2) .. 0] list

nine :: [a] -> [a]
nine [] = []
nine list = map (list !!) [u, p .. 0]
  where
    u = length list - 1
    p = length list - 2

ten :: [a] -> [a]
ten [] = []
ten list = [u, p .. 0] >>= (\i -> [list !! i])
    where
    u = length list - 1
    p = length list - 2

eleven :: [a] -> [a]
eleven [] = []
eleven list = [list !! x
              | x <- [length list - 1, length list - 2 .. 0]]

-- (1,"!amanap ,lanac a ,nalp a ,nam A")
-- (2,"!amanap ,lanac a ,nalp a ,nam A")
-- (3,"!amanap ,lanac a ,nalp a ,nam A")
-- (4,"!amanap ,lanac a ,nalp a ,nam A")
-- (5,"!amanap ,lanac a ,nalp a ,nam A")
-- (6,"!amanap ,lanac a ,nalp a ,nam A")
-- (7,"!amanap ,lanac a ,nalp a ,nam A")
-- (8,"!amanap ,lanac a ,nalp a ,nam A")
-- (9,"!amanap ,lanac a ,nalp a ,nam A")
-- (10,"!amanap ,lanac a ,nalp a ,nam A")
-- (11,"!amanap ,lanac a ,nalp a ,nam A")
-- (1,[4,3,2,1])
-- (2,[4,3,2,1])
-- (3,[4,3,2,1])
-- (4,[4,3,2,1])
-- (5,[4,3,2,1])
-- (6,[4,3,2,1])
-- (7,[4,3,2,1])
-- (8,[4,3,2,1])
-- (9,[4,3,2,1])
-- (10,[4,3,2,1])
-- (11,[4,3,2,1])
-- (1,[])
-- (2,[])
-- (3,[])
-- (4,[])
-- (5,[])
-- (6,[])
-- (7,[])
-- (8,[])
-- (9,[])
-- (10,[])
-- (11,[])