dailycoding17.hs

-- Project Euler : Problem 17
-- 1000の時にスペースを入れてしまっていたのを修正

numToStr :: Int -> String
numToStr 1  = "one"
numToStr 2  = "two"
numToStr 3  = "three"
numToStr 4  = "four"
numToStr 5  = "five"
numToStr 6  = "six"
numToStr 7  = "seven"
numToStr 8  = "eight"
numToStr 9  = "nine"
numToStr 10 = "ten"
numToStr 11 = "eleven"
numToStr 12 = "twelve"
numToStr 13 = "thirteen"
numToStr 14 = "fourteen"
numToStr 15 = "fifteen"
numToStr 16 = "sixteen"
numToStr 17 = "seventeen"
numToStr 18 = "eighteen"
numToStr 19 = "nineteen"
numToStr 20 = "twenty"
numToStr 30 = "thirty"
numToStr 40 = "forty"
numToStr 50 = "fifty"
numToStr 60 = "sixty"
numToStr 70 = "seventy"
numToStr 80 = "eighty"
numToStr 90 = "ninety"
numToStr 1000 = "onethousand"
numToStr x
    | x <  100 = numToStr (x - (x `mod` 10)) ++ numToStr (x `mod` 10)
    | x >= 100 = if (x `mod` 100 == 0)
                 then numToStr (x `div` 100) ++ "hundred"
                 else numToStr (x `div` 100) ++ "hundredand" ++ numToStr (x `mod` 100)

main = print $ sum $ map length $ map numToStr [1..1000]

-- 21124
-- ./dailycoding17  0.01s user 0.00s system 80% cpu 0.008 total