Pagini recente » Istoria paginii utilizator/switylove | Cod sursa (job #2497068)
#include <fstream>
unsigned N;
unsigned 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 phi(int n)
{
int nr = n;
for (int d = 2; n > 1 && d * d <= n; ++d)
{
if (n % d == 0)
{
nr = nr / d * (d - 1);
while (n % d == 0)
{
n /= d;
}
}
}
if (n > 1)
{
nr = nr / n * (n - 1);
}
return nr;
}
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;
}