Cod sursa(job #2659739)

Utilizator MaDragMaria-Bianca Dragan MaDrag Data 17 octombrie 2020 13:09:44
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp-64 Status done
Runda Arhiva educationala Marime 0.35 kb
Raporteaza aceasta sursa 
#include <fstream>
#include <cmath>

using namespace std;

int main() {
ifstream fin("ciur.in");
ofstream fout("ciur.out");

bool a[2000001];
int nr=0, n, i, j;
fin>>n;
for (i=2;i<=n;i++)
  a[i]=1;
for (i=2;i<=sqrt(n);i++)
 if (a[i])
  for (j=i;j<=n/i;j++)
     a[i*j]=0;
for (i=2;i<=n;i++)
  if (a[i]) nr++;
fout<<nr;

return 0;
}