Cod sursa(job #272909)
Utilizator | Data | 7 martie 2009 22:26:31 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.35 kb |
#include<fstream.h>
#include<math.h>
ifstream fin("ciur.in");
ofstream fout("ciur.out");
int ciur[2000001];
long long int n;
int main()
{int i,j,nr=0;
fin>>n;
for(i=2;i<=sqrt(n);i++)
if(ciur[i]==0)
for(j=2;i*j<=n;j++)
ciur[i*j]=1;
for(i=2;i<=n;i++)
if(ciur[i]==0) nr++;
fout<<nr;
fin.close();
fout.close();
return 0;
}