Cod sursa(job #669627)
Utilizator | Data | 27 ianuarie 2012 14:46:05 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.3 kb |
#include<cstdio>
#include<bitset>
using namespace std;
bitset<2000005> a;
int main () {
int i,j,n,k;
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf("%d",&n);
for(i=2;i*i<=n;++i)
if(a[i]==0)++k;
for(j=i*i;j<=n;j+=i)
a[j]=1;
printf("%d",k);
return 0;
}