Cod sursa(job #1326738)
Utilizator | Data | 25 ianuarie 2015 21:47:22 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.41 kb |
#include <fstream>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
int n;
char prim[2000001];
int main()
{
int nr=0;
fin>>n;
for(int i=2;i<=n;i++)
prim[i]=1;
for(int i=2;i<=n;i++)
if(prim[i]){
nr++;
for(int j=i+i;j<=n;j+=i)
prim[j]=0;}
fout<<nr;
fin.close();
fout.close();
return 0;
}