Cod sursa(job #2759082)
Utilizator | Data | 15 iunie 2021 11:54:34 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
#include <fstream>
using namespace std;
bool v[1999999];
int main() {
ifstream fin("ciur.in");
ofstream fout("ciur.out");
int n;
fin >> n;
for (int i = 2; i * i <= n; ++i) {
if (!v[i]) {
for (int k = 2; i * k <= n; ++k) {
v[i * k] = true;
}
}
}
int cnt_prime_numbers = 0;
for (int i = 2; i <= n; ++i) {
if (!v[i]) {
++cnt_prime_numbers;
}
}
fout << cnt_prime_numbers;
return 0;
}