結果

問題 No.154 市バス
コンテスト
ユーザー AyachiGin
提出日時 2016-06-11 16:13:31
言語 Haskell
(9.10.1)
結果
WA  
実行時間 -
コード長 1,158 bytes
コンパイル時間 2,181 ms
コンパイル使用メモリ 170,496 KB
実行使用メモリ 14,976 KB
最終ジャッジ日時 2024-10-13 08:25:29
合計ジャッジ時間 8,301 ms
ジャッジサーバーID
（参考情報） 		judge2 / judge5
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 -- * 1
other AC * 2 WA * 5 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:40:18: warning: [GHC-63394] [-Wx-partial]
    In the use of ‘head’
    (imported from Prelude, 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."
   |
40 |                  head xs == 'G' && length xs >= 2 && all (=='W') xs
   |                  ^^^^
[2 of 2] Linking a.out

ソースコード

diff # 

module Main where

main :: IO ()
main = do
  i <- readLn
  s <- getContents
  mapM_ (putStrLn . isPossible) . take i . lines $ s

-- | tests
-- >>> isPossible "WWWWWWWWWGR"
-- "possible"
-- >>> isPossible "WWWWGWGRR"
-- "possible"
-- >>> isPossible "WWWWWWWWWWWWWWGRRG"
-- "impossible"
-- >>> isPossible "WGRWGR"
-- "possible"
-- >>> isPossible "WWWWWWWWWWWWWWWWWGGWGWGGWGWGGGWGG"
-- "impossible"
-- >>> WGWR
-- "impossible"
-- >>> WGRW
-- "impossible"
isPossible :: String -> String
isPossible s = if take1RGW s then
                 "possible"
               else
                 "impossible"
  where
    take1RGW = takeR . reverse
    takeR :: String -> Bool
    takeR ('R':'G':ls) = length ls > 0 && all (=='W') ls || takeG ('G':ls)
    takeR ('R':xs) = takeG xs
    takeR _ = False
    takeG xs = if elem 'R' xs then
                 case break (=='G') xs of
                  (_, "") -> False
                  (ys, (_:zs)) -> takeW (ys ++ zs)
               else
                 head xs == 'G' && length xs >= 2 && all (=='W') xs
    takeW xs
      | elem 'W' xs = let (as, (_:bs)) = break (=='W') xs in takeR $ as ++ bs
      | otherwise   = False
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