Data commit

Task/Anti-primes/Swift/anti-primes.swift

@@ -0,0 +1,54 @@
+extension BinaryInteger {
+  @inlinable
+  public func countDivisors() -> Int {
+    var workingN = self
+    var count = 1
+
+    while workingN & 1 == 0 {
+      workingN >>= 1
+
+      count += 1
+    }
+
+    var d = Self(3)
+
+    while d * d <= workingN {
+      var (quo, rem) = workingN.quotientAndRemainder(dividingBy: d)
+
+      if rem == 0 {
+        var dc = 0
+
+        while rem == 0 {
+          dc += count
+          workingN = quo
+
+          (quo, rem) = workingN.quotientAndRemainder(dividingBy: d)
+        }
+
+        count += dc
+      }
+
+      d += 2
+    }
+
+    return workingN != 1 ? count * 2 : count
+  }
+}
+
+var antiPrimes = [Int]()
+var maxDivs = 0
+
+for n in 1... {
+  guard antiPrimes.count < 20 else {
+    break
+  }
+
+  let divs = n.countDivisors()
+
+  if maxDivs < divs {
+    maxDivs = divs
+    antiPrimes.append(n)
+  }
+}
+
+print("First 20 anti-primes are \(Array(antiPrimes))")