Cod sursa(job #1642417)
Utilizator | Data | 9 martie 2016 14:01:28 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.52 kb |
#include <cmath>
#include <fstream>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
const int NMax = 2000005;
bool prim[NMax];
int N, Nr;
void Ciur()
{
for(int i = 2; i <= N; i++)
prim[i] = 1;
for(int i = 2; i <= N; i++)
if(prim[i])
{
Nr++;
for(int j = i + i; j <= N; j += i)
prim[j] = 0;
}
}
int main()
{
fin>>N;
Ciur();
fout<<Nr<<"\n";
return 0;
}