Cod sursa(job #399382)
Utilizator | Data | 20 februarie 2010 13:46:27 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.33 kb |
#include<fstream.h>
#include<math.h>
ifstream f("ciur.in");
ofstream g("ciur.out");
int prim(int x)
{int d=3;
if(x==1 || (x>2 && x%2==0)) return 0;
else while(d<=sqrt(x))
if(x%d==0) return 0;
else d=d+2;
return 1;
}
int main()
{
long i,n,nr=0;
f>>n;
for(i=2;i<=n;i++)
if(prim(i)==1) nr++;
g<<nr;
return 0;
}