Playing around with primes

Prime Fun

// Mark: - Prime fun

// isPrime function
func isPrime(n: Int) -> Bool {
    guard n > 1 else { return false }
    
    for i in stride(from: n-1, to: 1, by: -1) {
        if n % i == 0 {
            return false
        }
    }

    return true
}

print("isPrime", isPrime(n: 17))

func nextPrime(from n: Int) -> Int {
    var nextPrime = n + 1
    
    while !isPrime(n: nextPrime) {
        nextPrime += 1
    }
    
    return nextPrime
}

print("next prime", nextPrime(from: 17))

// Prime factors for a number
func primeFactorization(n: Int) -> [Int] {
    var remaining = n
    var currentPrime = 2
    
    var result = [Int]()
    
    while remaining > 1 {
        while (remaining % currentPrime == 0) {
            result.append(currentPrime)
            remaining /= currentPrime
        }
        
        currentPrime = nextPrime(from: currentPrime)
    }
    
    return result
}

print("prime factors", primeFactorization(n: 20))