EKG sequence convergence: Difference between revisions

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=={{header|Haskell}}==

<lang Haskell>import Data.List (findIndex, isPrefixOf, tails)

import Data.~~List~~

import Data.Maybe (fromJust)

import Data.Maybe

seqEKGRec :: Int -> Int -> [Int] -> [Int]

~~seqEKG_rec~~ _ 0 l = l

seqEKGRec _ 0 l = l

~~seqEKG_rec~~ k n [] = ~~seqEKG_rec~~ k (n - 2) [k, 1]

seqEKGRec k n [] = seqEKGRec k (n - 2) [k, 1]

~~seqEKG_rec~~ k n l@(h:t) =

seqEKGRec k n l@(h:t) =

⚫

~~seqEKG_rec k~~ (n - 1)

seqEKGRec

⚫

([head (filter (\i -> (notElem i l) && ((gcd h i) > 1)) [2..])] ++ l)

k

⚫

(n - 1)

⚫

(head (filter (\i -> notElem i l && (gcd h i > 1)) [2 ..]) : l)

seqEKG k n = ~~reverse~~ ~~(seqEKG_rec k n~~ [])

seqEKG :: Int -> Int -> [Int]

seqEKG k n = reverse (seqEKGRec k n [])

main :: IO ()

⚫

~~main~~ = ~~mapM_~~ ~~(\x~~ -> (putStr "EKG (" >> (putStr . show $ x) >> putStr ") is " >> ~~print (seqEKG x 20)))~~

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

print ((+1) $ fromJust $ findIndex (isPrefixOf (take 20 (repeat True)))

((+ 1) $

⚫

(tails (zipWith (~~\x y -> (x~~==y)) (seqEKG 7 80) (seqEKG 5 80))))

fromJust $

</lang>

findIndex

(isPrefixOf (replicate 20 True))

⚫

(tails (zipWith (==) (seqEKG 7 80) (seqEKG 5 80))))</lang>

⚫

<pre>EKG (2) is [1,2,4,6,3,9,12,8,10,5,15,18,14,7,21,24,16,20,22,11]

<pre>

⚫

EKG (2) is [1,2,4,6,3,9,12,8,10,5,15,18,14,7,21,24,16,20,22,11]

EKG (5) is [1,5,10,2,4,6,3,9,12,8,14,7,21,15,18,16,20,22,11,33]

EKG (7) is [1,7,14,2,4,6,3,9,12,8,10,5,15,18,16,20,22,11,33,21]

EKG (9) is [1,9,3,6,2,4,8,10,5,15,12,14,7,21,18,16,20,22,11,33]

EKG (10) is [1,10,2,4,6,3,9,12,8,14,7,21,15,5,20,16,18,22,11,33]

EKG(5) and EKG(7) converge at 21

EKG(5) and EKG(7) converge at 21</pre>

</pre>

=={{header|J}}==