Cod sursa(job #1978024)
Utilizator | Data | 6 mai 2017 19:06:15 | |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva educationala | Marime | 0.41 kb |
#include <fstream>
using namespace std;
ifstream f("ciur.in");
ofstream g("ciur.out");
int n, v[2000005];
int main()
{
int i, k;
f >> n;
for (i = 2;i <= 2000005;i++)
v[i] = i;
for (i = 2;i <= 2000005;i++)
if (v[i])
{
k = 2;
while (i*k <= 2000005)
{
v[i*k] = 0;
k++;
}
}
k = 0;
for (i = 1;i <= n;i++)
if (v[i])
k++;
g << k << "\n";
return 0;
}