Count in factors: Difference between revisions

Content added Content deleted

Inline

@@ Line 3,665: / Line 3,665: @@
 =={{header|Scala}}==
-<lang scala>def primeFactors( n:Int ) = {
+<lang scala>
+object CountInFactors extends App {
-  def primeStream(s: Stream[Int]): Stream[Int] = {
+  def primeFactors(n: Int): List[Int] = {
-    s.head #:: primeStream(s.tail filter { _ % s.head != 0 })
-  }
-  val primes = primeStream(Stream.from(2))
+    def primeStream(s: LazyList[Int]): LazyList[Int] = {
+      s.head #:: primeStream(s.tail filter {
+        _ % s.head != 0
+      })
+    }
+    val primes = primeStream(LazyList.from(2))
+    def factors(n: Int): List[Int] = primes.takeWhile(_ <= n).find(n % _ == 0) match {
+      case None => Nil
+      case Some(p) => p :: factors(n / p)
+    }
+    if (n == 1) List(1) else factors(n)
+  }
+  // A little test...
-  def factors( n:Int ) : List[Int] = primes.takeWhile( _ <= n ).find( n % _ == 0 ) match {
+  {
-    case None => Nil
-    case Some(p) => p :: factors( n/p )
+    val nums = (1 to 12).toList :+ 2144 :+ 6358
+    nums.foreach(n => println("%6d : %s".format(n, primeFactors(n).mkString(" * "))))
   }
-  if( n == 1 ) List(1) else factors(n)
-}
-// A little test...
-{
-  val nums = (1 to 12).toList :+ 2144 :+ 6358
-  nums.foreach( n => println( "%6d : %s".format( n, primeFactors(n).mkString(" * ") ) ) )
 }
 </lang>