Embd.ly Challenge

embedly-1.hs

-- Sum Of Digits
sod = go 0
  where go acc i | i == 0    = acc
                 | otherwise = go (r+acc) q 
                   where (q,r) = quotRem i 10
                         
solve n = go 1 facs              
        where go j (a:as) | sod a == n = j
                          | otherwise  = go (j+1) as
              facs = scanl1 (*) [1..] -- save some recomputation
              
main = print $ solve 8001

embedly-2.hs

-- primitive html parser
html2depth = go [] 0 []
  where go :: [Int] -> Int -> [String] -> String -> [Int]
        go acc 0 _  "" = acc
        go acc d ts ('<':'p':'>':rs) = go (d:acc) (d+1) ("p":ts) rs
        go acc d (t:ts) ('<':'/':rs)  | t == s = go acc (d-1) ts $ dropWhile (/= '<') rs 
                     where s = takeWhile (/= '>') rs
        go acc d ts ('<':rs) = go acc (d+1) (s:ts) $ dropWhile (/= '<') rs 
                     where s = takeWhile (/= '>') rs                
        go acc d ts rs = go acc d ts $ dropWhile (/= '<') rs
                           
solve ls = sqrt $ q/n
  where n = fromIntegral $ length ls'
        s = sum ls'
        q = sum $ map (\i -> (i-m)^2) ls'
        m = s / n
        ls' :: [Double]
        ls' = map fromIntegral ls

-- call as "embedly-2 < input.html"
-- strip everything before and after article tag first
main = interact (show . solve . html2depth)

embedly-3.hs

solve n = (1+) $ length $ takeWhile (<t) $ scanl1 (+) fs'
  where fs = [1..n]            -- no need 
        m = foldl1 lcm fs      -- for fractions
        fs' = map (m `div`) fs
        
        t = (sum fs') `div` 2  -- half of 'all' the words
        
main = print $ solve 900