Cod sursa(job #732200)
Utilizator | Data | 9 aprilie 2012 21:01:33 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.35 kb |
#include <fstream>
#include <math.h>
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<=sqrtl(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;
fout.close();
return 0;
}