Cod sursa(job #531266)

Utilizator belicosuspusherino TALENT belicosus Data 9 februarie 2011 12:06:51
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.33 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int e[1000000];
int main()
{
	int n,i,j,nr=0;
	in>>n;
	for(i=2;i<=n;i++)
		e[i]=i;
	for(i=2;i<=n;i++)
		if(e[i]==i)
			for(j=i;j<=n;j+=i)
				e[j]=e[j]/i*(i-1);
	for(j=2;j<=n;j++)
		nr+=e[j];
	nr*=2;
	nr++;
	out<<nr;
}