Cod sursa(job #1236575)

Utilizator tavitTeodorescu Octavian tavit Data 2 octombrie 2014 09:28:22
Problema Ciurul lui Eratosthenes Scor 100
Compilator cpp Status done
Runda Arhiva educationala Marime 0.35 kb
Raporteaza aceasta sursa 
#include <iostream>
#include <fstream>

using namespace std;
long n,i,j,nr=0;
bool ok[20000001];
int main()
{ifstream f("ciur.in");
ofstream g("ciur.out");
f>>n;
for (i=1;i<=n;i++) ok[i]=true;
for (i=2;i*i<=n;i++)
{
    if (ok[i]) for (j=2*i;j<=n;j+=i) ok[j]=false;
}
for (i=2;i<=n;i++)
if (ok[i]==true) nr++;
g<<nr;

    return 0;
}