Cod sursa(job #669077)
Utilizator | Ababab psycho21r | Data | 26 ianuarie 2012 01:08:07 |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.44 kb |
#include <fstream>
using namespace std;
int main()
{
int n,phi[1000000],total=0;;
ifstream in("fractii.in");
in >> n;
in.close();
for (int i = 1; i <= n; ++i)
phi[i] = i-1;
for (int i = 2; i <= n; ++i)
{
for (int j = 2*i; j <= n; j+=i)
phi[j] -= phi[i];
total+=phi[i];
}
ofstream out("fractii.out");
out << 2*total + 1;
out.close();
return 0;
}