Data update

Task/Blum-integer/Scala/blum-integer.scala

@@ -0,0 +1,62 @@
+import scala.collection.mutable
+
+object BlumInteger extends App {
+  var blums = new Array[Int](50)
+  var blumCount = 0
+  val lastDigitCounts = mutable.Map[Int, Int]()
+  var number = 1
+
+  while (blumCount < 400_000) {
+    val prime = leastPrimeFactor(number)
+    if (prime % 4 == 3) {
+      val quotient = number / prime
+      if (quotient != prime && isPrimeType3(quotient)) {
+        if (blumCount < 50) {
+          blums(blumCount) = number
+        }
+        lastDigitCounts(number % 10) = lastDigitCounts.getOrElse(number % 10, 0) + 1
+        blumCount += 1
+        if (blumCount == 50) {
+          println("The first 50 Blum integers:")
+          blums.grouped(10).foreach(group => println(group.map(i => f"$i%3d").mkString(" ")))
+          println("")
+        } else if (blumCount == 26828 || blumCount % 100_000 == 0) {
+          println(f"The ${blumCount}th Blum integer is: $number%7d")
+          if (blumCount == 400_000) {
+            println("\nPercent distribution of the first 400000 Blum integers:")
+            lastDigitCounts.foreach { case (key, count) =>
+              println(f"    ${count.toDouble / 4000}%6.3f%% end in $key")
+            }
+          }
+        }
+      }
+    }
+    number += (if (number % 5 == 3) 4 else 2)
+  }
+
+  def isPrimeType3(aNumber: Int): Boolean = {
+    if (aNumber < 2) return false
+    if (aNumber % 2 == 0) return aNumber == 2
+    if (aNumber % 3 == 0) return aNumber == 3
+
+    var divisor = 5
+    while (divisor * divisor <= aNumber) {
+      if (aNumber % divisor == 0) return false
+      divisor += 2
+    }
+    aNumber % 4 == 3
+  }
+
+  def leastPrimeFactor(aNumber: Int): Int = {
+    if (aNumber == 1) return 1
+    if (aNumber % 2 == 0) return 2
+    if (aNumber % 3 == 0) return 3
+
+    var divisor = 5
+    while (divisor * divisor <= aNumber) {
+      if (aNumber % divisor == 0) return divisor
+      divisor += 2
+    }
+    aNumber
+  }
+}