Cod sursa(job #1119653)
Utilizator | Data | 24 februarie 2014 19:12:53 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.36 kb |
#include<fstream>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
bool x[4000000];
int main()
{
long long n,i,j,nr=0;
fin>>n;
nr++; // numaram 2-ul
for(i=3; i<=n; i=i+2)
{
if(x[i]==0)
nr++;
for(j=i*i; j<=n; j=j+2*i)
x[j]=1;
}
fout<<nr;
return 0;
}