Cod sursa(job #581642)

Utilizator alexalbu95Albu Alexandru alexalbu95 Data 14 aprilie 2011 14:22:01
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 f("fractii.in");
ofstream g("fractii.out");
long long n, i, j, a[10000000], k;
int main()
{ f>>n;
  for(i=1; i<=n; ++i) a[i]=i;
  for(i=2; i<=n; ++i) 
   { if(a[i]==i)
	   for(j=i; j<=n; j+=i) a[j]=a[j]/i*(i-1);
     k+=2*a[i];
   }
   ++k;
   g<<k;
   f.close();
   g.close();
   return 0;
}