Data commit

Task/Summarize-primes/Scala/summarize-primes.scala

@@ -0,0 +1,23 @@
+object PrimeSum extends App {
+
+  val oddPrimes: LazyList[Int] = 3 #:: LazyList.from(5, 2)
+        .filter(p => oddPrimes.takeWhile(_ <= math.sqrt(p)).forall(p % _ > 0))
+  val primes = 2 #:: oddPrimes
+
+  def isPrime(n: Int): Boolean = {
+    if (n < 5) (n | 1) == 3
+    else primes.takeWhile(_ <= math.sqrt(n)).forall(n % _ > 0)
+  }
+
+  val limit = primes.takeWhile(_ <= 1000).length
+
+  val number = (1 to limit).filter(index => {
+        val list = primes.take(index)
+        val sum = list.sum
+        val flag = isPrime(sum)
+        if (flag) println(f"$index%3d  ${list.last}%3d  $sum%5d")
+        flag
+      }).length
+
+  println(s"\nfound $number such primes")
+}