Cod sursa(job #229450)

Utilizator vlad_DVlad Dumitriu vlad_D Data 10 decembrie 2008 11:41:19
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.33 kb
Raporteaza aceasta sursa 
#include <cstdio>

#include <bitset>
using namespace std;
bitset<2000001> ciur;
int main() {
freopen("ciur.in", "r", stdin);
freopen("ciur.out", "w", stdout);
int n;
scanf("%d", &n);
int cnt = 0;

for (int i = 2; i <= n; ++i) if (!ciur[i]) {
	cnt++;
	for (int j = i << 1; j <= n; j+=i) ciur[j] = 1;
}
printf("%d\n", cnt);
return 0;
}