Cod sursa(job #292600)
Utilizator | Data | 31 martie 2009 12:12:14 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.31 kb |
#include <fstream.h>
#include <math.h>
int main ()
{
ifstream f ("ciur.in");
ofstream g ("ciur.out");
long a[2000000],n,i,j,l=0;
f>>n;
for (i=1;i<=n;i++) a[i]=0;
for (i=2;i<=sqrt(n);i++)
if (a[i]==0)
for (j=i+i;j<=n-i;j=j+i) a[j]=1;
for (i=2;i<=n;i++) if (a[i]==0) l++;
g<<l<<'\n';
return 0;
}