Cod sursa(job #256334)

Utilizator edward93Murica Edward Cristian edward93 Data 11 februarie 2009 16:21:59
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.35 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;
const int N=2000001;
int main()
{
	ifstream in("ciur.in");
	ofstream out("ciur.out");
	char c[N]={0};
	int n,k=0;
	in>>n;
	for (int i=2;i*i<=n;i++)
		if (c[i]==0)
			for (int j=i*i;j<=n;j=j+i)
				c[j]=1;
	for (int i=2;i<=n;i++)
		if (c[i]==0)
			k++;
out<<k;
in.close();
out.close();
return 0;
}