Cod sursa(job #302847)
Utilizator | Alexandra alex@ndra | Data | 9 aprilie 2009 12:33:53 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.42 kb |
#include<fstream>
using namespace std;
char prim[2000001];
long n, i, j, nr=0;
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+=i)
prim[j]=0;
}
ofstream g("ciur.out");
g<<nr;
g.close();
return 0;
}