Cod sursa(job #1245338)
| Utilizator |  Amarinei Neculai Amarinei |
Data | 18 octombrie 2014 23:17:01 |
|---|---|---|---|
| Problema | Fractii | Scor | 0 |
| Compilator | cpp | Status | done |
| Runda | Arhiva de probleme | Marime | 0.32 kb |
#include<fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int n,i,j,v[1000001];
long s;
int numarare(int n)
{for(i=2;i<n;i++)v[i]=i-1;
for(i=2;i<=n/2;i++)
for(j=i+i;j<=n;j+=i)v[j]-=v[i];
for(i=2;i<=n;i++)s+=2*v[i];
return s;
}
int main()
{f>>n;
g<<numarare(n);
return 0;
}