Cod sursa(job #3232090)
Utilizator | Data | 28 mai 2024 20:38:05 | |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.54 kb |
#include <fstream>
using namespace std;
ifstream cin("fractii.in");
ofstream cout("fractii.out");
int n, phi[1000001], sum;
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
for (int i = 1; i <= n; i++)
phi[i] = i;
for (int i = 2; i <= n; i++) {
if (phi[i] == i) {
for (int j = i; j <= n; j += i) {
phi[j] -= phi[j] / i;
}
}
}
for (int i = 2; i <= n; i++)
sum += phi[i];
cout << 2 * sum + 1;
return 0;
}