50 lines
1.1 KiB
Haskell
50 lines
1.1 KiB
Haskell
import Data.List (findIndex, isPrefixOf, tails)
|
|
import Data.Maybe (fromJust)
|
|
|
|
----------------------- EKG SEQUENCE ---------------------
|
|
|
|
seqEKGRec :: Int -> Int -> [Int] -> [Int]
|
|
seqEKGRec _ 0 l = l
|
|
seqEKGRec k n [] = seqEKGRec k (n - 2) [k, 1]
|
|
seqEKGRec k n l@(h : t) =
|
|
seqEKGRec
|
|
k
|
|
(pred n)
|
|
( head
|
|
( filter
|
|
(((&&) . flip notElem l) <*> ((1 <) . gcd h))
|
|
[2 ..]
|
|
) :
|
|
l
|
|
)
|
|
|
|
seqEKG :: Int -> Int -> [Int]
|
|
seqEKG k n = reverse (seqEKGRec k n [])
|
|
|
|
|
|
--------------------- CONVERGENCE TEST -------------------
|
|
main :: IO ()
|
|
main =
|
|
mapM_
|
|
( \x ->
|
|
putStr "EKG ("
|
|
>> (putStr . show $ x)
|
|
>> putStr ") is "
|
|
>> print (seqEKG x 20)
|
|
)
|
|
[2, 5, 7, 9, 10]
|
|
>> putStr "EKG(5) and EKG(7) converge at "
|
|
>> print
|
|
( succ $
|
|
fromJust $
|
|
findIndex
|
|
(isPrefixOf (replicate 20 True))
|
|
( tails
|
|
( zipWith
|
|
(==)
|
|
(seqEKG 7 80)
|
|
(seqEKG 5 80)
|
|
)
|
|
)
|
|
)
|