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June 24, 2022 19:07
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C# Prime Sieve
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/* | |
* Sieve of Eratosthene, C# implementation by George Corkery (github.com/gpc91) | |
* Something made for fun, feel free to use without attribution | |
* For more about the Sieve of Eratosthene, see this wikipedia page: https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes | |
*/ | |
using System; | |
using System.Collections.Generic; | |
class Eratosthene | |
{ | |
// Warning: Don't set this too high, trust me, scary things will happen. | |
void Sieve(int prime_target = 1000) | |
{ | |
List<int> numbers = new List<int>(); | |
// populate numbers list (2 -> prime_target). | |
for (int i = 2; i < prime_target; i++) | |
{ | |
numbers.Add(i); | |
} | |
// The actual sieve: sieve out non-prime numbers leaving only primes behind. | |
for (int p = 0; p < numbers.Count; p++) | |
{ | |
for (int n = numbers[p]; n < numbers.Count; n++) | |
{ | |
if (numbers[n] % numbers[p] == 0) | |
{ | |
numbers.Remove(numbers[n]); | |
} | |
} | |
} | |
// print the numbers left in our list. As the numbers list has been sieved the only numbers left should be prime | |
foreach (int prime in numbers) | |
{ | |
Console.Write($"{prime}, "); | |
} | |
} | |
} |
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