Cod sursa(job #1427373)
Utilizator | Data | 2 mai 2015 01:18:39 | |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.53 kb |
#include <iostream>
using namespace std;
int main()
{
freopen("fractii.in", "r", stdin);
freopen("fractii.out", "w", stdout);
int n;
cin >> n;
int *v = (int *)calloc(n + 1, sizeof(int));
long long nr = 0;
int *phy = (int *) calloc(n + 1, sizeof(int));
for (int i = 0; i <= n; i++)
phy[i] = i;
for (int i = 2; i <= n; i++)
{
if (!v[i])
{
for (int j = i; j <= n; j += i)
{
v[j] = i;
phy[j] /= i;
phy[j] *= i - 1;
}
}
nr += phy[i];
}
cout << nr * 2 + 1;
}