Cod sursa(job #732120)

Utilizator MichelJumatate Teodor-Mihail Michel Data 9 aprilie 2012 18:42:56
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.31 kb
Raporteaza aceasta sursa 
#include<fstream> 
using namespace std;
long n,i,j,a[1000001]; 
long long s; 
int main()
{
	ifstream f("fractii.in");
	ofstream g("fractii.out");
	f>>n;
	for(i=1;i<=n;i++)
		a[i]=i-1; 
	for(i=2;i<=n;i++) for(j=2;i*j<=n;j++)
		a[i*j]-=a[i]; 
	s=1; 
	for(i=1;i<=n;i++)
		s+=2*a[i]; 
	g<<s;
	return 0; 
}