Stable marriage implementation in Scala

contents/stable_marriage_problem/code/scala/stable_marriage.scala

@@ -0,0 +1,65 @@
+import scala.collection.mutable._
+
+object StableMarriage {
+
+ var bachelors = Queue[Man]()
+
+ case class Man(name: String, var preferences: List[Woman] = List()) {
+ def propose(): Unit = preferences match {
+ case woman :: remainingPreferences => {
+ if (woman.prefers(this)) {
+ bachelors ++= woman.fiance
+ woman.fiance = Some(this)
+ }
+ else
+ bachelors.enqueue(this)
+ preferences = remainingPreferences
+ }
+ case _ =>
+ }
+ }
+
+ case class Woman(name: String, var preferences: List[Man] = List(), var fiance: Option[Man] = None) {
+ def prefers(man: Man): Boolean =
+ fiance match {
+ case Some(otherMan) => preferences.indexOf(man) < preferences.indexOf(otherMan)
+ case _ => true //always prefer any man over nobody
+ }
+ }
+
+ def findStableMatches(men: Man*): Unit = {
+ bachelors = men.to[Queue]
+ while (bachelors.nonEmpty)
+ bachelors.dequeue.propose()
+ }
+}
+
+object StableMarriageExample {
+
+ val a = StableMarriage.Man("Adam")
+ val b = StableMarriage.Man("Bart")
+ val c = StableMarriage.Man("Colm")
+ val x = StableMarriage.Woman("Xena")
+ val y = StableMarriage.Woman("Yeva")
+ val z = StableMarriage.Woman("Zara")
+
+ a.preferences = List(y, x, z)
+ b.preferences = List(y, z, x)
+ c.preferences = List(x, z, y)
+ x.preferences = List(b, a, c)
+ y.preferences = List(c, a, b)
+ z.preferences = List(a, c, b)
+
+
+ def main(args: Array[String]): Unit = {
+
+ StableMarriage.findStableMatches(a, b, c)
+
+ List(x, y, z).foreach(
+ w => Console.println(
+ w.name
+ + " is married to "
+ + w.fiance.getOrElse(StableMarriage.Man("Nobody")).name))
+ }
+
+}

contents/stable_marriage_problem/stable_marriage_problem.md

@@ -46,6 +46,8 @@ I am incredibly interested to see what you guys do and how you implement the alg
 [import, lang:"java"](code/java/stable-marriage.java)
 {% sample lang="php" %}
 [import, lang:"php"](code/php/stable_marriage.php)
+{% sample lang="scala" %}
+[import, lang:"scala"](code/scala/stable_marriage.scala)
 {% endmethod %}
 
 <script>