Cod sursa(job #915242)

Utilizator TudorMTudor Moldovanu TudorM Data 14 martie 2013 20:54:31
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.33 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;
ifstream f("ciur.in");
ofstream g("ciur.out");
int i, n, k, j;
bool v[2000001];
int main()
{
	f>>n;
	v[2]=1;
	for(i=3;i<=n;i+=2)
	{
		if(v[i]==0)
		{
		for(j=i+i;j<=n;j+=i)
			v[j]=1;
		}
	}
	for(i=1;i<=n;i+=2)
		if(v[i]==0)k++;
	g<<k;
	f.close();
	g.close();
	return 0;
}