Cod sursa(job #643244)

Utilizator alexclpAlexandru Clapa alexclp Data 3 decembrie 2011 11:36:08
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.31 kb
Raporteaza aceasta sursa 
#include <fstream>

using namespace std;

bool c[2000000];

int main ()
{
	int n,i,j,p=0;
	ifstream in("ciur.in");
	ofstream out("ciur.out");
	in >> n;
	for (i=2;i*i<=n;i++) {
		if (!c[i]) {
			for (j=i*i;j<=n;j+=i)
				c[j]=true;
		}
	}
	for (i=2;i<=n;i++) 
		if (!c[i]) p++;
	out << p;
	return 0;
}