Cod sursa(job #2451278)
Utilizator | William Damian Balint WilIiamper | Data | 26 august 2019 13:19:39 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.51 kb |
#include <fstream>
#include <cmath>
#define NMax 2000000
using namespace std;
int main()
{
ifstream fin ("ciur.in");
ofstream fout ("ciur.out");
int n, nr = 0;
bool ciur[NMax];
fin >> n;
for (int i = 2; i <= n; ++i)
ciur[i] = 1;
for (int i = 2; i * i <= n; ++i)
if (ciur[i])
for (int j = i + i; j <= n; j = j + i)
ciur[j] = 0;
for (int i = 2; i <= n; ++i)
if (ciur[i])
++nr;
fout << nr;
return 0;
}