Cod sursa(job #688163)

Utilizator pandreeaePopescu Andreea pandreeae Data 23 februarie 2012 09:11:45
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.33 kb
Raporteaza aceasta sursa 
#include <fstream>
#include <bitset>
using namespace std;
bitset <2000006> v;

int main ()
{
	ifstream in ("ciur.in");
	ofstream out ("ciur.out");
	long long i, j, e=1, n;
	in>>n;
	for(j=4;j<=n;j+=2) 
			v[j]=1;
	for(i=3;i<=n;i+=2){
 		if(v[i]==0){
			e++;
			for(j=i*i;j<=n;j+=2*i) 
				v[j]=1;}}
	out<<e;
	return 0;
}