Cod sursa(job #1012493)

Utilizator sulzandreiandrei sulzandrei Data 19 octombrie 2013 10:26:28
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.32 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;
int n,a[1000001],i,j;
long long nr;
ifstream f("fractii.in");
ofstream g("fractii.out");

int main() {
f>>n;
for (i=2;i<=n;++i)
    a[i]=i-1;
for (i=2;2*i<=n;++i)
    for (j=2*i;
     j<=n; j+=i)
      a[j]-=a[i];
for (i=2; i<=n;++i)
 nr+=a[i];
g<<2*nr+1;
return 0;
}