Scalazの練習。GCJJのAを解いてみた。

gistfile1.scala

import java.io._
import scala.io._
import scalaz._
import Scalaz._
import effects._
import IterV._

object A extends App {

  val PairRegex = """(\d+) (\d+)""".r

  val TripleRegex = """(\d+) (\d+) (\d+)""".r

  val file = new File(args.head)

  def cases(list: List[String]) = {
    val triple = (list: List[String]) => list.collect {
      case TripleRegex(m, c, w) => (m.toInt, c.toInt, w.toInt)
    }
    val pair = (list: List[String]) => {
      val pairZero = mzero[(Int, Int)]
      val pairs = list.map {
	case PairRegex(a, b) => (a.toInt, b.toInt)
	case _ => pairZero
      }
      pairs.selectSplit(pairZero /==)
    }
    (triple *** pair).apply(list.pair).fold(_ zip _).zipWithIndex.map {
      case (((m, c, w), pairs), i) => {
	val index = i |+| 1
	val cards = pairs.foldl[IndexedSeq[Int]](1 to m) { (cards, pair) =>
	  pair match {
	    case (a, b) => cards.splitAt(a - 1) match {
	      case (x, tail) => tail.splitAt(b) match {
		case (y, z) => y <+> x <+> z
	      }
	    }
	  }
	}
	val n = cards -!- (w - 1)
	"Case #" |+| index.shows |+| ": " |+| n.shows
      }
    }
  }

  val main = for {
    lines <- getFileLines(file)(drop(1) >|> collect[String, List]).map(_.run)
    writer = new PrintWriter("A-small-practice.out")
    _ <- io(writer).bracket(w => io(w.close))(w => cases(lines).traverse_(wPutStrLn(w, _)))
  } yield ()

  main.unsafePerformIO

}