結果

問題 No.3 ビットすごろく
ユーザー mtwtkman
提出日時 2023-05-16 19:40:33
言語 Haskell
(9.10.1)
結果
AC  
実行時間 311 ms / 5,000 ms
コード長 1,061 bytes
コンパイル時間 10,355 ms
コンパイル使用メモリ 169,600 KB
実行使用メモリ 8,448 KB
最終ジャッジ日時 2024-12-14 18:06:49
合計ジャッジ時間 15,473 ms
ジャッジサーバーID
（参考情報） 		judge3 / judge5
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ファイルパターン 結果
other AC * 33
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:41:22: 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."
   |
41 |   n :: Int <- read . head <$> prompt
   |                      ^^^^
[2 of 2] Linking a.out

ソースコード

diff # 

split :: String -> [String]
split = go ("", [])
  where
    go :: (String, [String]) -> String -> [String]
    go (a, acc) "" = acc <> [a]
    go (a, acc) (' ' : xs) = go ("", acc <> [a]) xs
    go (a, acc) (x : xs) = go (a <> [x], acc) xs

prompt :: IO [String]
prompt = do split <$> getLine

bin :: Int -> [Int]
bin x
  | x <= 1 = [x]
  | otherwise =
      let (n, r) = x `quotRem` 2
       in bin n <> [r]

step :: Int -> Int
step = sum . bin

solve :: Int -> Int
solve n = go [(1, 1)] []
  where
    go :: [(Int, Int)] -> [Int] -> Int
    go [] _ = -1
    go ((p, c) : qs) visited =
      if p == n
        then c
        else
          let prev = p - step p
              next = p + step p
              canPrev = prev > 0 && notElem prev visited
              canNext = next <= n && notElem next visited
              q = [(prev, c + 1) | canPrev] <> [(next, c + 1) | canNext]
              v' = [prev | canPrev] <> [next | canNext]
           in go (qs <> q) (v' <> visited)

main :: IO ()
main = do
  n :: Int <- read . head <$> prompt
  print $ solve n
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