Cod sursa(job #1665594)
Utilizator | MateiStefan MateiAruxandei | Data | 27 martie 2016 09:50:02 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.38 kb |
#include <fstream>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
long long nmax,c[20000000],i,nr,j,m;
int main()
{
fin>>nmax;
c[0]=c[1]=1;
for(i=2;i*i<=nmax;i++)
if(c[i]==0)
for(m=2;m*i<=nmax;m++)
c[m*i]=1;
for(i=1;i<=nmax;i++)
if(c[i]==0)
nr++;
fout<<nr;
return 0;
}