Cod sursa(job #356052)
Utilizator | Andrei matzipan | Data | 13 octombrie 2009 12:57:42 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.33 kb |
#include <fstream>
using namespace std;
ifstream in("ciur.in");
ofstream out("ciur.out");
unsigned long N,i,v[2000000];
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;
for(i=2; i<=N; i++) v[i]=1;
out<<era();
return 0;
}