Cod sursa(job #1280223)

Utilizator andrei_bB. Andrei andrei_b Data 1 decembrie 2014 16:32:59
Problema Fractii Scor 90
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");

long long n,i,j,a[1000001],suma;

int main()
{
    fin>>n;
    for ( i=2 ; i<=n ; i++ ) {
        a[i]+=i-1;
        for ( j=i+i ; j<=n ; j+=i )
                a[j]-=a[i];
        suma+=a[i];

    }
    fout<<suma*2+1;

}