2019-09-12 10:33:56 -07:00
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import Data.List (isPrefixOf)
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mapping = [("M",1000),("CM",900),("D",500),("CD",400),("C",100),("XC",90),
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("L",50),("XL",40),("X",10),("IX",9),("V",5),("IV",4),("I",1)]
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toArabic :: String -> Int
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toArabic "" = 0
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toArabic str = num + toArabic xs
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where (num, xs):_ = [ (num, drop (length n) str) | (n,num) <- mapping, isPrefixOf n str ]
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