Haskell競技プログラミング用メモ

文字列

Data.ByteString.Chan8

#Data.Vector.Unboxed
create, unfoldrN, fusion

Data.Vector.Unboxed.Mutable

new, read, modify, write, freeze, thaw

データ構造

priority queue →　Data.Set
グラフの構築やdfs →　Data.Graph

再帰

foldl',foldr(早期リターン)

Prelude

IO

a1-an読み込み

import qualified Data.Vector.Unboxed as VU
import qualified Data.ByteString.Char8 as B

main = do
  let readInt = fmap (second B.tail) . B.readInt
 
  as <- VU.unfoldrN n readInt <$> B.getLine

ABを読み取り

import qualified Data.Vector.Unboxed as VU
import qualified Data.ByteString.Char8 as B

main = do
  let readInt = fmap (second B.tail) . B.readInt
 
  (a,b) <- (\vec -> (vec VU.! 0, vec VU.! 1)) . VU.unfoldrN 2 readInt <$> B.getLine

A1B1A2B2...AnBn

import qualified Data.Vector.Unboxed as VU
import qualified Data.ByteString.Char8 as B

main = do
  let readInt = fmap (second B.tail) . B.readInt
 
  abs <-
    VU.replicateM n $ (\vec -> (vec VU.! 0, vec VU.! 1)) . VU.unfoldrN 2 readInt <$> B.getLine

IOまとめ

readInt = fst . fromJust . BS.readInt
readIntList = map readInt . BS.words
getInt = readInt <$> BS.getLine
getIntList = readIntList <$> BS.getLine

パフォーマンスの目安

実行時間はC++の５倍以内を目指す