Sorry, My mistake, that function has to be like this. But the results
are decreased.
524752 primes founds in 10 seconds Highest Prime is :7761499
double sr = Math.Sqrt(Num);
foreach(int n in primes)
{
if (n > sr)
return true;
if (Num % n == 0)
return false;
}
return true;
if there is a direct method to find the max index of list, where
number is less than the sqrt of that number, results would have been
better. here writing 2 if conditions taking time.
On Nov 12, 11:12 pm, CK <[EMAIL PROTECTED]> wrote:
> I'm not too sure about this line....
>
> if (n > Math.Sqrt(n))
> return true;
>
> On 12 Nov, 10:22, ram <[EMAIL PROTECTED]> wrote:
>
> > With the below configuration i got 7746653 primes founds in 10
> > seconds Highest Prime is :15493305
>
> > CPU: Intel Pentiun E2140@ Dual 1.60GHZ
> > RAM: 2GB
> > OS: Windows 2003 Server
> > .Net: 2.0
>
> > I used different logic. because suppose to decide a number whether
> > it is prime number or not, we no need to check all the numbers below
> > the square root of that number. IF we check all the primes of below
> > the square root of that number, its enough. because except 1 , atleast
> > 1 factor of non-primary number must be a primary number. using this
> > principle, we can find quicker than checking all numbers under the
> > sqrt of the number.
>
> > List<int> primes = new List<int>();
> > protected void Page_Load(object sender, EventArgs e)
> > {
> > int seconds = 10;
> > primes.Add(2);
> > primes.Add(3);
> > primes[1] = 3;
> > DateTime x, y = DateTime.Now;
> > int a = 4, b = 2;
> > do
> > {
> > if (IsPrim(a))
> > {
> > primes.Add(a);
> > b++;
> > }
> > a++;
> > x = DateTime.Now;
> > } while ((x - y).TotalSeconds < seconds);
> > Response.Write(b.ToString() + " primes founds in " +
> > seconds+ " seconds");
> > Response.Write("Highest Prime is :" + primes[primes.Count -
> > 1].ToString());
> > }
>
> > private bool IsPrim(int Num)
> > {
> > foreach(int n in primes)
> > {
> > if (Num % n == 0)
> > return false;
> > if (n > Math.Sqrt(n))
> > return true;
> > }
> > return true;
> > }
>
> > On Nov 11, 2:10 pm, CK <[EMAIL PROTECTED]> wrote:
>
> > > This is something I've been working on for a while, and I thought it
> > > might be fun to push it out to the group to see if anyone can better
> > > my efforts.
>
> > > The challange is to write a Windows Console App that generates prime
> > > numbers. It does not need to generate them in any specific order,
> > > record them, or even catch all primes. The aim is to calculate as
> > > many unique primes as possible in 10 seconds.
>
> > > Obviously, this will depend on the processor it runs on, so that will
> > > be taken into account.
>
> > > Once you have a solution, please post your results like the following:
> > > (this is example data only)
>
> > > CPU: Intel E6300
> > > Cores: 2
> > > RAM: 1GB
> > > OS: Vista Home Premium
> > > .Net: 3.5
> > > Number of primes in 10 seconds: 10,000
> > > Highest Prime found: 123247
>
> > > To confirm your code is working properly, please post some large
> > > primes (~100000) your code has found to verify that it is working
> > > correctly.
>
> > > Please also be willing to share your code.
>
> > > Please enter, just for fun, and enjoy :)
>
> > > PS. A Prime is a number that is only divisible by itself and 1. 1 is
> > > not a prime, 2 is, 3 is, 4 isn't, 5 is etc.
