Cod sursa(job #3122154)
Utilizator | Ionescu Raul David ionescuraul26 | Data | 17 aprilie 2023 15:27:37 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.54 kb |
#include <iostream>
#include <fstream>
#include <bitset>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
const int MAX_LENGTH = 2000000;
bitset<MAX_LENGTH + 1> primeNumsIndex;
int main() {
int n, primeNumsCnt = 0;
fin >> n;
for (int i = 2; i <= n; ++i) {
if (primeNumsIndex[i] == 0) {
++primeNumsCnt;
for (int d = 2; i * d <= n; ++d) {
primeNumsIndex[i * d] = 1;
}
}
}
fout << primeNumsCnt;
return 0;
}