求素数算法

  public static int[] PrimeList;
         public static void FindPrime(int n)
         {
              int[] IntList;
              int len=n-1;
              IntList=new int[n];
              for (int p=2;p<=n;p++) IntList[p-1]=p;
              for (int p=2;p<Math.Sqrt(n);p++)
              {
                   if (IntList[p-1]==0) continue;
                   int j=p*p;
                   while (j<=n)
                   {
                       if (IntList[j-1]!=0 )
                       {
                            IntList[j-1]=0;
                            len=len-1;
                       }
                       j=j+p;
                   }
              }
              PrimeList=new int[len];
              int i=0;
              for (int p=2;p<=n;p++)
              {
                   if (IntList[p-1]!=0)
                   {
                       PrimeList[i]=IntList[p-1];
                       i=i+1;
                   }                 
              }
         }