結果

問題 No.583 鉄道同好会
ユーザー pekempey
提出日時 2017-10-28 03:35:58
言語 Haskell
(9.10.1)
結果
TLE  
(最新)
AC  
(最初)
実行時間 -
コード長 1,194 bytes
コンパイル時間 3,247 ms
コンパイル使用メモリ 195,200 KB
実行使用メモリ 66,304 KB
最終ジャッジ日時 2024-11-22 00:30:42
合計ジャッジ時間 11,234 ms
ジャッジサーバーID
（参考情報） 		judge1 / judge3
このコードへのチャレンジ
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ファイルパターン 結果
sample AC * 3
other AC * 15 TLE * 1
権限があれば一括ダウンロードができます
コンパイルメッセージ
Loaded package environment from /home/judge/.ghc/x86_64-linux-9.8.2/environments/default
[1 of 2] Compiling Main             ( Main.hs, Main.o )

Main.hs:20:50: warning: [GHC-63394] [-Wx-partial]
    In the use of ‘head’
    (imported from Data.List, but defined in GHC.List):
    "This is a partial function, it throws an error on empty lists. Use pattern matching or Data.List.uncons instead. Consider refactoring to use Data.List.NonEmpty."
   |
20 |                       then let reachable = dfs ((head . head) g) [] (toArray n g)
   |                                                  ^^^^

Main.hs:20:57: warning: [GHC-63394] [-Wx-partial]
    In the use of ‘head’
    (imported from Data.List, but defined in GHC.List):
    "This is a partial function, it throws an error on empty lists. Use pattern matching or Data.List.uncons instead. Consider refactoring to use Data.List.NonEmpty."
   |
20 |                       then let reachable = dfs ((head . head) g) [] (toArray n g)
   |                                                         ^^^^
[2 of 2] Linking a.out

ソースコード

diff # 

import Data.List
import Control.Applicative
import Debug.Trace
import Data.Array
import Data.Array.ST
import Control.Monad
import Control.Monad.ST

main :: IO ()
main = solve <$> (map read . words <$> getLine) <*> (map (map read . words) . lines <$> getContents) >>= putStrLn . yesno

yesno :: Bool -> String
yesno True = "YES"
yesno False = "NO"

solve :: [Int] -> [[Int]] -> Bool
solve [n, m] [] = True
solve [n, m] g = let deg = (map length . group . sort . concat) g
                 in if (all even) deg || (length . filter odd) deg == 2
                      then let reachable = dfs ((head . head) g) [] (toArray n g)
                           in (sort . nub) reachable == (sort . nub . concat) g
                      else False

toArray :: Int -> [[Int]] -> Array Int [Int]
toArray n es = runST $ do
  g <- newArray (0, n-1) [] :: ST s (STArray s Int [Int])
  forM_ es $ \[x, y] -> do
    readArray g x >>= writeArray g x . (y:)
    readArray g y >>= writeArray g y . (x:)
  freeze g

dfs :: Int -> [Int] -> Array Int [Int] -> [Int]
dfs u vis g = foldl' f (u:vis) (g ! u)
  where
    f :: [Int] -> Int -> [Int]
    f vis v
      | v `elem` vis = vis
      | otherwise    = dfs v vis g
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