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/* The Computer Language Shootout
http://shootout.alioth.debian.org/
contributed by Yura Taras
modified by Isaac Gouy
*/
object chameneos {
abstract class Colour
case object RED extends Colour
case object YELLOW extends Colour
case object BLUE extends Colour
case object FADED extends Colour
val colours = List(RED, BLUE, YELLOW, FADED)
class MeetingPlace(var n: Int) {
var other: Creature = _
def meet(c: Creature) = synchronized {
if(n > 0) {
if(other == null) {
other = c;
this.wait()
} else {
other.setOther(c.colour)
c.setOther(other.colour)
other = null
n = n - 1
this.notify()
}
} else {
c.setOther(FADED)
}
}
}
class Creature(private val mp: MeetingPlace, var colour: Colour) extends Thread {
private var met = 0
var other: Colour = _
def setOther(_o: Colour) {
other = _o
}
def getCreaturesMet = met
override def run() {
try {
while(colour != FADED) {
mp.meet(this)
if(other == FADED) {
colour = FADED
} else {
met = met + 1
colour = complement(other)
}
}
} catch {
case e:InterruptedException => () // Let the thread exit
}
}
def complement(other: Colour) = (colour, other) match {
case (RED, YELLOW) => BLUE
case (RED, BLUE) => YELLOW
case (RED, RED) => RED
case (YELLOW, BLUE) => RED
case (YELLOW, RED) => BLUE
case (YELLOW,YELLOW) => YELLOW
case (BLUE, RED) => YELLOW
case (BLUE, YELLOW) => RED
case (BLUE, BLUE) => BLUE
case (FADED, _) => FADED
}
}
def apply(n: Int) {
val mp = new MeetingPlace(n)
val creatures = for(x <- colours) yield {
val cr = new Creature(mp, x);
cr.start();
cr
}
creatures.foreach(x => x.join)
val meetings = (creatures foldLeft 0) {(x, y) => (x + y.getCreaturesMet)}
Console.println(meetings)
}
def main(args: Array[String]) {
if(args.length < 1) throw new IllegalArgumentException();
chameneos(Integer.parseInt(args(0)))
}
}
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