Cod sursa(job #2759378)
Utilizator | Data | 17 iunie 2021 12:26:46 | |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.44 kb |
#include <fstream>
using namespace std;
const int VMAX = 1000010;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n;
long long int sol;
int euler[VMAX];
int main() {
fin >> n;
for (int i = 2; i <= n; i++)
euler[i] = i - 1;
for (int i = 2; i <= n; i++) {
sol += euler[i];
for (int j = 2 * i; j <= n; j += i)
euler[j] -= euler[i];
}
fout << 2 * sol + 1 << '\n';
fout.close();
return 0;
}