Cod sursa(job #3208674)
Utilizator | Andrei Pirjol andreipirjol5 | Data | 29 februarie 2024 11:51:37 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.53 kb |
#include <fstream>
using namespace std;
ifstream fin ("ciur.in");
ofstream fout ("ciur.out");
const int NMAX = 2 * (1e6);
int ciur[NMAX + 5];
void Ciur()
{
ciur[1] = 1;
for(int i = 2; i * i <= NMAX; i++)
for(int j = 2 * i; j <= NMAX; j += i)
ciur[j] = 1;
}
int main()
{
int n;
fin >> n;
Ciur();
int cnt = 0;
for(int i = 1; i <= n; i++)
if(ciur[i] == 0)
cnt++;
fout << cnt;
fin.close();
fout.close();
return 0;
}