Cod sursa(job #1972258)
Utilizator | FMI Tilica Robert Robert29 | Data | 22 aprilie 2017 16:47:29 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.45 kb |
#include<fstream>
#define N 2000001
using namespace std;
ifstream cin("ciur.in");
ofstream cout("ciur.out");
int EratostenesSieve(int n)
{
bool sieve[n+1];
int nr = 0;
for(int i = 2; i <= n; ++i)
{
if(!sieve[i])
{
++nr;
for(int j = 2 * i; j <= n; j += i)
{
sieve[j] = true;
}
}
}
return nr;
}
int main(){
int n;
cin >> n;
cout<< EratostenesSieve(n);
cin.close();
cout.close();
return 0;
}