Another programming challenge was to determine the 5000th prime number. A common way to quickly calculate prime numbers is using a sieve. There are several that you can choose from, I chose to implement Eratasthenes sieve. The code below will allow you to get all the prime numbers up to a limit.

public class EratosthenesSieve { public static IEnumerablePrimeNumbers(int limit) { // add 1 to the limit to determine the limit number itself as well BitArray bitArray = new BitArray(limit + 1, true); bitArray[0] = false; bitArray[1] = false; bitArray[2] = true; yield return 2; for (int i = 4; i < bitArray.Length; i += 2) { bitArray[i] = false; } for (int i = 3; i < bitArray.Length; i++) { if (bitArray[i]) { yield return i; for (int x = i * 2; x < bitArray.Length; x += i) { bitArray[x] = false; } } } } }

Interesting way of doing it, I like the deferred execution.

Jake May 2, 2016 11:48:27 PM

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