Cod sursa(job #2083771)
Utilizator | Bogdan Sever-Cristian severut | Data | 8 decembrie 2017 09:15:06 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.5 kb |
#include <iostream>
#include <fstream>
#include <math.h>
using namespace std;
ifstream fin ("ciur.in");
ofstream fout ("ciur.out");
bool c[2000005];
int main()
{
int n,contor,aux;
fin>>n;
contor=0;
for (int i=2;i<=sqrt(n);i++)
{
if (c[i]==0)
for (int j=i+i;j<=n;j=j+i)
c[j]=1;
}
for (int i=2;i<=n;i++)
if (c[i]==0)
contor++;
fout<<contor;
fin.close();
fout.close();
return 0;
}