Cod sursa(job #661831)

Utilizator StickmanLazar Alexandru Stickman Data 15 ianuarie 2012 12:47:06
Problema Ciurul lui Eratosthenes Scor 0
Compilator cpp Status done
Runda Arhiva educationala Marime 0.34 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;

int main()
{
	long long a,b,nr=1,n;	
	char v[2000001];
	ifstream in("ciur.in");
	in>>n;
	in.close();
	for(a=2; a<=n; a++)
		v[a]=1;
	for(a=3; a*a<=n; a+=2)
		if(v[a]==1)
		{	nr++;
			for(b=3; b*a<=n; b++)
				v[a*b]=0;
		}
	ofstream out("ciur.out");
	out<<nr;
	out.close();
	return 0;
  }