Cod sursa(job #296671)
Utilizator | Ranca Razvan Haggis | Data | 4 aprilie 2009 23:57:13 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.31 kb |
#include<fstream>
#include<stdlib>
using namespace std;
ifstream in("ciur.in");
ofstream out("ciur.out");
long n,i,d,j,nr;
char v[2000100];
int main ()
{
in>>n;
nr=1;
v[1]=1;
for(i=3;i<=n;i+=2)
{
if(!v[i])
nr++;
for(d=i*i;d<=n;d+=i)
v[d]=1;
}
out<<nr;
return 0;
}