Cod sursa(job #303685)
Utilizator | Data | 10 aprilie 2009 10:37:23 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.36 kb |
#include<fstream>
using namespace std;
char prim[2000001];
long nr=0,i,n,j;
int main()
{
ifstream f("ciur.in");
f>>n;
f.close();
for(i=2;i<=n;i++)
prim[i]=1;
for(i=2;i<=n;i++)
if(prim[i])
{
nr++;
for(j=i+i;j<=n;j=j+i)
prim[j]=0;
}
ofstream g("ciur.out");
g<<nr;
g.close();
return 0;
}