Cod sursa(job #2497071)
Utilizator | Data | 21 noiembrie 2019 23:55:41 | |
---|---|---|---|
Problema | Fractii | Scor | 70 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.63 kb |
#include <fstream>
unsigned N;
long long S = 1;
unsigned phi(unsigned n)
{
unsigned result = n, p = 2;
while (p * p <= n)
{
if (n % p == 0)
{
result -= result / p;
}
while (n % p == 0)
{
n /= p;
}
++p;
}
if (n > 1)
{
result -= result / n;
}
return result;
}
int main()
{
std::ifstream fisierIN("fractii.in");
fisierIN >> N;
for (unsigned k = 2; k <= N; ++k)
{
S += 2 * phi(k);
}
std::ofstream fisierOUT("fractii.out");
fisierOUT << S;
}