Cod sursa(job #798825)

Utilizator tibi9876Marin Tiberiu tibi9876 Data 17 octombrie 2012 13:24:04
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.29 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;

int i,j,n,s,a[1000001];

int main()
{
	ifstream f("fractii.in");
	ofstream g("fractii.out");
	f >> n;
	for (i=1;i<=n;i++)
		a[i]=i-1;
	s=1;
	for (i=1;i<=n;i++)
	{
		for (j=2*i;j<=n;j+=i)
			a[j]-=a[i];
		s+=a[i]*2;
	}
	g << s;
	return 0;
}