Cod sursa(job #379361)
Utilizator | Data | 1 ianuarie 2010 00:51:03 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
#include <fstream>
#include <math.h>
using namespace std;
long j,a,i,n;
bool v[2000001];
int main()
{
ifstream f("ciur.in");
ofstream g("ciur.out");
f>>n;
a=0;
for (i=2;i<=n;i++)
v[i]=true;
for (i=2;i<=sqrt(n);i++)
if (v[i])
for (j=2;j<=n/i;j++)
v[i*j]=false;
for (i=2;i<=n-1;i++)
if (v[i])
a++;
g<<a;
f.close();
g.close();
return 0;
}