Cod sursa(job #481844)
Utilizator | Munteanu Valentin CyberneticLord | Data | 1 septembrie 2010 20:14:05 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.5 kb |
#include <fstream>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
int getTheNumber(int n)
{
int *p=new int[2000000];
int i, j, nr = 0;
for (i = 3; i <= n; i += 2)
{
if (p[i] == 0)
{
nr++;
for (j = i + i + i; j <= n; j += i << 1)
{
p[j] = 1;
}
}
}
return nr;
}
int main()
{
int n;
fin>>n;
fout<<getTheNumber(n);
fin.close();
fout.close();
return 0;
}