Cod sursa(job #1048980)

Utilizator ValeraShulghin Valera Valera Data 6 decembrie 2013 18:08:18
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 f("fractii.in");
ofstream g("fractii.out");

int a[1000000],i,j,n;
long long s;

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

    for (i=2;i<=n;i++)
        {
        s+=a[i];
        for (j=2*i;j<=n;j+=i)
            a[j]-=a[i];
        }
    g<<2*s+1;

}