akihiro4chawon

// お題：一方通行を許可した迷路を作成
// <http://d.hatena.ne.jp/aya_eiya/20110329/1301406161>
//
// deve68 さんの解答をそのまま scala に移植。（自分の理解用）
// 出典：<http://d.hatena.ne.jp/deve68/20110410/1302464249>

import java.awt.Dimension
import java.awt.geom.Point2D
import javax.swing.JFrame

akihiro4chawon

// お題：複数行にわたる printf

object Main extends Application {
  def multiPrintf[T <: Product](tuples: T*) =
    for (t <- tuples; pi = t.productIterator; fmt = pi.next.asInstanceOf[String])
      println(fmt.format(pi.toSeq :_*))
      
  multiPrintf(
      ("line1: %d", 1),
      ("line2: %d, %d", 1, 2),

akihiro4chawon

object FibImpModule {
  /** リファレンス実装 */
  val fibRef: Stream[BigInt] = 
    BigInt(0) #:: fibRef.scanLeft(BigInt(1)){_ + _}
  
  /** 逐次平方変換系の実装 */
  // Generic な実装 (しかし、JVMの型消去のため、実力よりずいぶん遅くなったため
  // 公正なベンチマークにならないのでボツ。。。)
  def fibSqr[IntT](n: Int)(implicit num: Integral[IntT]): IntT = {
    import num._

akihiro4chawon

object NumUtils {
  // 2x2行列（乗算/冪乗のみ定義）
  case class m2d[T](val a: T, val b: T, val c: T, val d: T)(implicit num: Numeric[T]) {
    import num._
    def *(that: m2d[T]) = m2d(
      this.a * that.a + this.b * that.c, this.a * that.b + this.b * that.d,
      this.c * that.a + this.d * that.c, this.c * that.b + this.d * that.d
    )
  def pow(exp: Int): m2d[T] = 
    if (exp == 0) m2d.eye[T]

akihiro4chawon

fib = [0:0, 1:1].withDefault{ n ->
  n % 2 ? (fib[n >> 1] ** 2 + fib[(n >> 1) + 1] ** 2) \
        : ((2 * fib[(n >> 1) - 1] + fib[n >> 1]) * fib[n >> 1])
}

akihiro4chawon

  def find2[A](x:A, xs:List[A]):Option[A] = {
    if(xs.nonEmpty){
      if(xs.head == x) Some(xs.head)
      else find2(x, xs.tail)
    } else {
      None
    }
  }
  def find3[A](x:A, xs:List[A]):Option[A] = 
    xs.headOption match {

akihiro4chawon

object Main {
  def humming: Iterator[BigInt] = {
    object ForwardReferenceable {
      def output: Iterator[BigInt] = Iterator(BigInt(3), BigInt(4), BigInt(5)) ++ merged
      val Seq(result, m2, m3, m5) = tee(output, 4)
      val merged = merge(m2 map {_ * 2}, m3 map {_ * 3}, m5 map {_ * 5})
    }
    Iterator(BigInt(1), BigInt(2)) ++ ForwardReferenceable.result
  }
  

akihiro4chawon

object Main extends App {
  "Method1: " +: Method1.answer take 10 foreach print
  println
  "Method2: " +: Method2.answer take 10 foreach print
  println
  
  assert((Method1.answer take 10000) == (Method2.answer take 10000))
  println("Assertion succeeded")
  
  def time[U](proc: => U) = {

akihiro4chawon

object Memoize {

  // 1変数関数をメモ化する(2変数以上は tupled/untupledで対応)
  def memoize[ArgT, RetT](f: ArgT => RetT): ArgT => RetT = {
    val memo = scala.collection.mutable.Map.empty[ArgT, RetT]
    arg => memo.getOrElseUpdate(arg, f(arg))
  }
  
  // scala 2.9.0.RC1 or later
  def memoize[T1, T2, R](f: Function2[T1, T2, R]): Function2[T1, T2, R] =

akihiro4chawon

// Akka's Pi Tutorial implemented with scala.collection.parallel

object PiParallel extends App {
  import scala.collection.GenSeq
  
  val seqRng = Range(0, 10000 * 10000).view
  val parRng = Range(0, 10000 * 10000).par.view
  
  def calculatePi(rng: GenSeq[Int]): Double =
    rng.map{i => 4.0 * (1 - (i % 2) * 2) / (2 * i + 1)}.sum;