Cod sursa(job #671637)

Utilizator TIBSTiberiu Iorgulescu 321CA TIBS Data 31 ianuarie 2012 18:33:01
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.35 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;

long n, i, j, phi[1000000], rez=0;
ifstream f("fractii.in");
ofstream g("fractii.out");
int main()
{f>>n;
f.close();
for(i=1;i<=n;i++)
	phi[i]=i;
for(i=2;i<=n;i++)
	if(phi[i]==i)
		for(j=i;j<=n;j+=i)
			phi[j]/=i, phi[j]*=(i-1);
for(i=2;i<=n;i++)
	rez+=phi[i];
g<<rez*2+1;
g.close();
return 0;
}