Cod sursa(job #1665619)
Utilizator | Data | 27 martie 2016 10:25:45 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.38 kb |
#include <fstream>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
int n,y,d,nr,i;
bool ciur[20000000];
int main()
{
fin>>n;
ciur[1]=1;
ciur[0]=0;
for(d=2;d*d<=n;d++)
if(ciur[d]==0)
for(y=2;y*d<=n;y++)
ciur[y*d]=1;
for(i=2;i<=n;i++)
if(ciur[i]==0)
nr++;
fout<<nr;
return 0;
}