Anti-primes: Difference between revisions

=={{header|Swift}}==

<lang swift>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))")</lang>

{{out}}

<pre>First 20 anti-primes are [1, 2, 4, 6, 12, 24, 36, 48, 60, 120, 180, 240, 360, 720, 840, 1260, 1680, 2520, 5040, 7560]</pre>