Daily Coding Problem: Problem #677

/**
 *The Sieve of Eratosthenes is an algorithm used to generate all prime numbers smaller than N.
 * The method is to take increasingly larger prime numbers, and mark their multiples as composite.
For example, to find all primes less than 100, we would first mark [4, 6, 8, ...] (multiples of two), then [6, 9, 12, ...] (multiples of three),
and so on. Once we have done this for all primes less than N, the unmarked numbers that remain will be prime.
Implement this algorithm.
Bonus: Create a generator that produces primes indefinitely (that is, without taking N as an input).
 * */
class Problem_677 {
    /*
    * Time complexity:O(n log logn)
    * */
    fun sieveOfEratosthenes(n: Int) {
        //finally return false if array[i] is not a Prime
        val primes = BooleanArray(n + 1) { true }
        primes[0] = false
        primes[1] = false
        for (i in 2..n) {
            if (primes[i]) {
                //println all prime
                print("$i,")
                var j = 2
                //update all multiples of i
                while (i * j <= n) {
                    primes[i * j] = false
                    j++
                }
            }
        }
    }
}