Data commit

Task/Attractive-numbers/Scala/attractive-numbers.scala

@@ -0,0 +1,28 @@
+object AttractiveNumbers extends App {
+  private val max = 120
+  private var count = 0
+
+  private def nFactors(n: Int): Int = {
+    @scala.annotation.tailrec
+    def factors(x: Int, f: Int, acc: Int): Int =
+      if (f * f > x) acc + 1
+      else
+        x % f match {
+          case 0 => factors(x / f, f, acc + 1)
+          case _ => factors(x, f + 1, acc)
+        }
+
+    factors(n, 2, 0)
+  }
+
+  private def ls: Seq[String] =
+    for (i <- 4 to max;
+         n = nFactors(i)
+         if n >= 2 && nFactors(n) == 1 // isPrime(n)
+         ) yield f"$i%4d($n)"
+
+  println(f"The attractive numbers up to and including $max%d are: [number(factors)]\n")
+  ls.zipWithIndex
+    .groupBy { case (_, index) => index / 20 }
+    .foreach { case (_, row) => println(row.map(_._1).mkString) }
+}