Cod sursa(job #1132637)

Utilizator stoicatheodorStt sas stoicatheodor Data 3 martie 2014 19:13:05
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.35 kb
Raporteaza aceasta sursa 
#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int n, v[1000002],i,j;
long long r;
int main()
{
    in>>n;
    for(i=2; i<=n; i++)
        v[i]=i-1;
    for(i=2; i<=n; i++)
    {
        r=r+v[i];
        for(j=i+i;j<=n;j+=i)
        v[j]=v[j]-v[i];
    }
    out<<r*2+1;
    return 0;

}