Cod sursa(job #2382591)
Utilizator | Vamanu Petru Gabriel petrisorvmy | Data | 18 martie 2019 15:16:02 |
---|---|---|---|
Problema | Ciurul lui Eratosthenes | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva educationala | Marime | 0.43 kb |
#include <fstream>
#define ll long long
using namespace std;
ifstream f("ciur.in");
ofstream g("ciur.out");
int n, sol;
bool v[2000001];
void ciur()
{
for(int i = 2 ; i * i<= n; ++i)
if(v[i] == 0)
for( int j = i*2; j<=n ; j += i)
v[j] = 1;
}
int main()
{
f>>n;
ciur();
v[1]= 1;
for( int i = 1; i<= n; ++i) if(v[i] == 0 ) sol++;
g << sol;
return 0;
}