Cod sursa(job #1910288)

Utilizator alexmihaitTuliga Mihai Alexandru alexmihait Data 7 martie 2017 16:19:02
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int main()
{
    int i,j,phi[1000000],n,r=1;
    in>>n;
    for(i=1;i<=n;i++)
     phi[i]=i-1;
    for(i=2;i<=n;i++)
     for(j=2*i;j<=n;j+=i)
      phi[j]-=phi[i];
    for(i=2;i<=n;i++)
     r+=phi[i]*2;
    out<<r<<'\n';
    return 0;
}