mynumber-possibility.hs

import qualified Data.Map as M (lookup)
import Data.Map (Map, fromList)
import Data.List (permutations)
import Data.Maybe (fromJust)

dictionaryFromList :: [Int] -> Map Char Int
dictionaryFromList xs = fromList $ zip ['a' .. 'j'] xs

transformByMap :: Ord a => [a] -> Map a b -> [b]
transformByMap xs dic = map (fromJust . flip M.lookup dic) xs

-- 桁の並びを反転したマイナンバー上位11桁から
-- チェックディジットを求める。
checkdigit_r :: [Int] -> Int
checkdigit_r xs = let
                c = 11 - (calc 1 xs) `mod` 11
              in
                if c >= 10 then 0 else c
              where
                calc n ys | n >= 12   = 0
                          | n >= 7    = head ys * (n - 5) + calc (n + 1) (tail ys)
                          | otherwise = head ys * (n + 1) + calc (n + 1) (tail ys)


verify :: [Int] -> Bool
verify xs = let (y:ys) = reverse xs
            in checkdigit_r ys == y

-- 'a' .. 'j' がそれぞれ 0 .. 9 のいずれかの数字と
-- 一対一対応する12文字の文字列のリストを受け取り、
-- (チェックディジットを満たす数, 満たさない数)
-- を返す。
possibility xss = let
           dictionaries  = map dictionaryFromList $ permutations [0..9]
           fromDicList   = map transformByMap xss
           verifyDic dic = and $ map (\fromDic -> verify $ fromDic dic) fromDicList
         in
           foldl (\(a, b) dic -> if verifyDic dic then (a + 1, b) else (a, b + 1))
                 (0, 0)
                 dictionaries

-- 適当に生成した10個で試しています。
main = print $ possibility [
                "gggfheiggejh", -- (666574866497)
                "bcheiggijdfi", -- (127486689358)
                "gcfijggiicfb", -- (625896688251)
                "igeihgfeacee", -- (864876540244)
                "jhbgcjijfege", -- (971629895464)
                "adjhhigiiefd", -- (039778688453)
                "bihgbggafced", -- (187616605243)
                "iidigaghjjjj", -- (883860679999)
                "ihahjggcdhif", -- (870796623785)
                "bbfbijeahfbf"  -- (115189407515)
        ]