Cod sursa(job #1388343)

Utilizator GinguIonutGinguIonut GinguIonut Data 15 martie 2015 13:33:53
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
#include <fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int i,j,n,v[1000001];
long long sum;
int main()
{
fin>>n;
for(i=2;i<=n;i++)
    v[i]=i-1;
for(i=2;i<=n;i++)
    {
        for(j=2*i;j<=n;j+=i)
            v[j]-=v[i];
        sum+=v[i];
    }
fout<<1ll*sum*2+1;
    return 0;
}