Cod sursa(job #356046)
Utilizator | Data | 13 octombrie 2009 12:51:22 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.37 kb |
#include <fstream>
using namespace std;
ifstream in("ciur.in");
ofstream out("ciur.out");
long N,nr,v[2000000];
void init() {
for(unsigned int i=2; i<=N; i++) v[i]=1;
}
long era() {
long x,nr,i;
nr=N;
for(i=2; i<=N; i++) if(v[i]!=0) for(x=i; x*i<N; x++)
{ nr--; v[i]=0; }
return nr;
}
int main() {
in>>N;
init();
nr=era();
out<<nr;
return 0;
}