Challenge
The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

Your task is to find the sum of all the primes below two million.

Time limit: nil

Goodluck,

Little cheat.

#include <windows.h>
#include <stdio.h>
#include <math.h>
void main()
{
	long sum, two_mil;
	two_mil = 10; /*change to 2 mil*/
	sum =0;
	bool prime;
	for (long x =2; x < two_mil; x++)
	{
		prime = false;
		for (long p = 2; p < x; p++)
		{
			if (fmod((double)x / (double)p,1)==0 && (x !=p))
				prime = true;
		}
		if(prime == false)
		sum+=x;
	}
	printf("%d\n", sum);
	system("pause";

}

yes it takes forever, #1. Just comment the windows header file and the last line.

// Outputs 142913828922 to the standard output stream.

what do you mean?

Yeah the answer is 142913828922

Here is my code:

class SumOfPrimes
{
	public static void main(String[] args)
	{
		long num = 2000000;
		long sum=0;
	
		for(long i=2; i<=num; i++){
			if(isPrime(i)){
				sum+=i;
			}
		}
		System.out.println(sum);
	}
	
	static boolean isPrime(long num)
	{
		for(long i=2; i<num; i++)
		{
			if((num%i)==0){
				return false;
			}
		}
		return true;
	}
}

@Dell and omo_to_dun, how long did it take your code to compute this?

hahaha you dont want to kno mine, How did you compute that time? UNIX feature or C

Yeah it wud and yope the brute force,  I use a Mac, wats d syntax? or rather how o i go about it, I normally use my text editor(TextMate).

hahaha yeah i type faster than my static keyboard now adays(effects of recursion), Was asking for the syntax for getting the run time of the program

hahaha. This is a project euler question

tundebabzy:

hahaha. This is a project euler question

So i heard I have a document filled with some terrible questions, these are the easy ones on the document, lmao

Is that it?

Yaay! thanks that worked!
So which is real, user and sys. What does each calculate

@Fayimora, you dont really want to know how long it takes

@omo, My systems both Linux and Windows output something different from your script.

omo_to_dun:

^
You are absolutely right. It implies that you are using a 32-bit system. My system is 64-bit. I am sorry for not initially making it portable for 32-bit systems. I have updated the code. It should now output correctly on your system. It was [i]s[/i]tupid of me to think that everyone is now running 64-bit systems. In case you are wondering: the answer (142913828922) is greater than the maximum representable positive integer by a size_t data type on a 32-bit system. A size_t happens to be 4 bytes on a 32-bit system, but 8 bytes on a 64-bit system. I have changed it to unsigned long long. Thank you very much. By the way, I noticed that you were running your system as the root user. Chei, oh boy, you get liver o. I don't trust myself to do that.

Wuss.

Nope. Here it is http://en.wikipedia.org/wiki/Sieve_of_Sundaram

omo_to_dun:

LOL. Now implement that in a programming language of your choice and let us analyze the runtime. I assume that you would decline!

I'm doing it, but its maxing out one out of four cores! Kinda like an infinite loop. Anyway, I'm still trying, don't want to steal anything off the internet.

omo_to_dun:

You have a quad core. That's cool. I should be getting one at the end of the year. Do you honestly notice any overall difference in performance? Or is it when you just use a special type of application?

Honestly, its both. It improves everything, from gta iv to boot time.

@fayimora your code is still compiling, 3 minutes gone.

Phucking Hell.