Cod sursa(job #432144)

Utilizator andunhillMacarescu Sebastian andunhill Data 1 aprilie 2010 21:28:33
Problema Fractii Scor 100
Compilator cpp Status done
Runda pregatire_2 Marime 0.33 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;
int main()
{ ifstream f("fractii.in");
  ofstream g("fractii.out");
 long long n,i,j,k=0; long long x[1000001];
 f>>n;
 for(i=2;i<=n;i++)
    x[i]=i-1; 
 for(i=2;i<=n;i++)
 {  k=k+x[i];
	for(j=i*2;j<=n;j+=i)
    x[j]-=x[i];
 }
 k=(k*2)+1;
 g<<k;
 f.close();
 g.close();
 return 0;
}