Cod sursa(job #1295095)
Utilizator | Radu Toporan RaduToporan | Data | 18 decembrie 2014 19:40:42 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.36 kb |
#include <cstdio>
bool a[2000001];
int n,i,j,nrprime=1;
int main()
{
freopen("ciur.in","r",stdin);
freopen("ciur.out","w",stdout);
scanf("%d",&n);
a[0]=1;
a[1]=1;
for (i=3; i*i<=n; i++) if (a[i]==0) for (j=i;j<=n/i;j++) a[i*j]=1;
for (i=1; i<=n; i=i+2) if (a[i]==0) nrprime++;
printf("%d",nrprime);
return 0;
}