Data commit

Task/Pernicious-numbers/Swift/pernicious-numbers.swift

@@ -0,0 +1,34 @@
+import Foundation
+
+extension BinaryInteger {
+  @inlinable
+  public var isPrime: Bool {
+    if self == 0 || self == 1 {
+      return false
+    } else if self == 2 {
+      return true
+    }
+
+    let max = Self(ceil((Double(self).squareRoot())))
+
+    for i in stride(from: 2, through: max, by: 1) where self % i == 0  {
+      return false
+    }
+
+    return true
+  }
+}
+
+public func populationCount(n: Int) -> Int {
+  guard n >= 0 else {
+      return 0
+  }
+
+  return String(n, radix: 2).lazy.filter({ $0 == "1" }).count
+}
+
+let first25 = (1...).lazy.filter({ populationCount(n: $0).isPrime }).prefix(25)
+let rng = (888_888_877...888_888_888).lazy.filter({ populationCount(n: $0).isPrime })
+
+print("First 25 Pernicious numbers: \(Array(first25))")
+print("Pernicious numbers between 888_888_877...888_888_888: \(Array(rng))")