Cod sursa(job #803147)
Utilizator | Data | 27 octombrie 2012 09:44:59 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.4 kb |
#include <fstream>
#include <math.h>
using namespace std;
ifstream f("ciur.in");
ofstream g("ciur.out");
bool a[2000000];
int nr=0,i,j,n;
int main()
{
f>>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++;
g<<nr;
f.close();
g.close();
}