(Problem 10)Summation of primes

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

Find the sum of all the primes below two million.

#include<stdio.h>
#include<string.h>
#include<math.h>
#include<ctype.h>
#include<stdlib.h>
#include<stdbool.h>

#define N 2000000

bool prim(int n)
{
	int i;
	for(i=2; i*i<=n; i++)
	{
		if(n%i==0)
			return false;
	}
	return true;
}

int main()
{
	int i;
	long long sum=2;
	for(i=3; i<=N; i=i+2)
	{
		if(prim(i))
		{
			sum+=i;
		}
	}
	printf("%lld\n",sum);

	return 0;
}

Answer:
142913828922

posted @ 2013-07-24 00:06  cpoint  阅读(216)  评论(0编辑  收藏  举报
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