DeepSearch.hs

import Control.Applicative ((<$>))
import Data.List (partition)

readNumList :: String -> [Int]
readNumList = map read . words

segmentsCount :: [Int] -> [[Int]] -> Int
segmentsCount [] _ = 0
segmentsCount (v:vs) edges = let (vs', es') = mark v vs edges in 1 + segmentsCount vs' es'

mark :: Int -> [Int] -> [[Int]] -> ([Int], [[Int]]) 
mark v vs es =
	let (adjEdges, another) = partition (elem v) es in
	let adj = map (head . filter (/= v)) adjEdges in
	foldl (\(vs, es) v -> mark v (filter (/= v) vs) es) (vs, another) adj

main :: IO ()
main = do
	[v, e] <- readNumList <$> getLine
	edges <- map readNumList <$> (sequence $ replicate e getLine)
	print $ segmentsCount [1..v] edges