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QuestionSieve of Eratosthenes Pin
WebMaster12-Sep-12 4:23
MemberWebMaster12-Sep-12 4:23 
I have implemented the "Sieve of Eratosthenes" algorithm in c# to find prime numbers below 2,000,000. The execution takes very time. How can I improve my implementation?

Here is my code:
C#
public class Number
{
   private int _Value;
   private bool _IsPrime;

   public int Value
   {
      get { return this._Value; }
      set { this._Value = value; }
   }
   public bool IsPrime
   {
      get { return this._IsPrime; }
      set { this._IsPrime = value; }
   }

   public Number(int value)
   {
       this.Value = value;
       this.IsPrim = true;
   }
}


C#
List<Number> numbers = new List<Number>();

for (int i = 2; i < 20000000; i++)
    numbers.Add(new Number(i));

for (int i = 0; i < numbers.Count - 1; i++)
   if (numbers[i].IsPrime)
      for (int j = i + 1; j < numbers.Count - 1; j++)
              if (numbers[j].Value % numbers[i].Value == 0)
                     numbers[j].IsPrime = false;

Meysam


modified 12-Sep-12 17:18pm.

AnswerRe: Sieve of Eratosthenes Pin
fjdiewornncalwe12-Sep-12 4:31
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