Cod sursa(job #1217092)
Utilizator | Data | 6 august 2014 16:17:30 | |
---|---|---|---|
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");
char v[2000000];
int main()
{
int i,j,contor=1;
int n;
fin>>n;
for(i=3;i<=n/2;i+=2)
if(!v[i])
{
for(j=i*i;j<=n;j+=i)
v[j]=1;
}
for(i=3;i<=n;i+=2)
if(!v[i])
contor++;
fout<<contor;
return 0;
}