Cod sursa(job #2661333)
Utilizator | Data | 21 octombrie 2020 19:35:18 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 70 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.5 kb |
#include <iostream>
#include <fstream>
//#include <bits/stdc++.h>
using namespace std;
ifstream fin("ciur.in");
ofstream fout("ciur.out");
int n, nr_prime;
int sir[2000001];
int main() {
fin >> n;
sir[1] = 1;
for (int i = 2; i <= n; ++i) {
if (sir[i] == 0) {
++nr_prime;
if (i * i <= n) {
for (int j = i + i; j <= n; j = j + i) {
sir[j] = 1;
}
}
}
}
fout << nr_prime;
return 0;
}