Intersecting number wheels: Difference between revisions

=={{header|Haskell}}==

Defining a unit movement of the interlocking wheels as a recursive descent,

terminating at the first digit found, and map-accumulating with that recursion over a list of given length.

<lang haskell>import qualified Data.Map.Strict as M

import Data.Maybe (fromMaybe)

import Data.List (mapAccumL)

import Data.Char (isDigit)

import Data.Bool (bool)

clockWorkTick :: M.Map Char String -> (M.Map Char String, Char)

clockWorkTick wheelMap =

let leftRotate = take . length <*> (tail . cycle)

click wheels name =

let wheel = fromMaybe ['?'] (M.lookup name wheels)

v = head wheel

in bool

click

(,)

(isDigit v)

(M.insert name (leftRotate wheel) wheels)

v

in click wheelMap 'A'

main :: IO ()

main =

mapM_ print $

(flip (mapAccumL (const . clockWorkTick)) [1 .. 20] . M.fromList) <$>

[ [('A', "123")]

, [('A', "1B2"), ('B', "34")]

, [('A', "1DD"), ('D', "678")]

, [('A', "1BC"), ('B', "34"), ('C', "5B")]

]</lang>

{{Out}}

<pre>(fromList [('A',"312")],"12312312312312312312")

(fromList [('A',"21B"),('B',"43")],"13214213214213214213")

(fromList [('A',"D1D"),('D',"786")],"16718617816718617816")

(fromList [('A',"C1B"),('B',"34"),('C',"5B")],"13514314513413514314")</pre>