Data update

Task/Parallel-calculations/Scala/parallel-calculations.scala

@@ -0,0 +1,56 @@
+import scala.collection.parallel.CollectionConverters._
+
+case class PrimeFactorInfo(
+                            number: Int,
+                            smallestPrimeFactor: Int,
+                            primeFactors: List[Int]
+                          )
+
+def isPrime(n: Int): Boolean = {
+  @annotation.tailrec
+  def checkDivisor(d: Int): Boolean = {
+    if (d * d > n) true
+    else if (n % d == 0) false
+    else checkDivisor(d + 2)
+  }
+
+  if (n < 2) false
+  else if (n == 2 || n == 3) true
+  else if (n % 2 == 0 || n % 3 == 0) false
+  else checkDivisor(5)
+}
+
+def primeFactorInfo(n: Int): PrimeFactorInfo = {
+  require(n > 1, "Number must be more than one")
+
+  @annotation.tailrec
+  def factorize(num: Int, currentFactor: Int = 2, factors: List[Int] = Nil): List[Int] = {
+    if (num == 1) factors.reverse
+    else if (isPrime(num)) (num :: factors).reverse
+    else if (num % currentFactor == 0) factorize(num / currentFactor, currentFactor, currentFactor :: factors)
+    else {
+      val nextFactor = if (currentFactor == 2) 3 else currentFactor + 2
+      factorize(num, nextFactor, factors)
+    }
+  }
+
+  val factors = if (isPrime(n)) List(n)
+  else factorize(n).sorted
+
+  PrimeFactorInfo(n, factors.min, factors)
+}
+
+object ParallelCalculations extends App {
+
+  private val numbers: List[Int] = List(
+    12757923, 12878611, 12878893, 12757923, 15808973, 15780709, 197622519
+  )
+  private val info: List[PrimeFactorInfo] = numbers.par.map(primeFactorInfo).toList
+  private val maxFactor: Int = info.map(_.smallestPrimeFactor).max
+  private val results: List[PrimeFactorInfo] = info.filter(_.smallestPrimeFactor == maxFactor)
+
+  println(s"The following number(s) have the largest minimal prime factor of $maxFactor:")
+  results.foreach { result =>
+    println(s"  ${result.number} whose prime factors are ${result.primeFactors.mkString(", ")}")
+  }
+}