isPrime

isPrime

//http://stackoverflow.com/questions/5811151/why-do-we-check-upto-the-square-root-of-a-prime-number-to-determine-if-it-is-pri

func isPrime(n: Int) -> Bool {
    if n < 2 {
        return false // are not primes
    }
    var limit = Int(sqrt(Float(n)))
    if limit < 2 {
       return true // 2, 3 are primes
    }
    for i in 2...limit {
        if n % i == 0 {
            return false
        }
    }
    return true
}