Cod sursa(job #819533)

Utilizator valentinpielePiele Valentin valentinpiele Data 19 noiembrie 2012 11:10:44
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.3 kb
#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*j]-a[i];
s=1;
for(i=1;i<=n;i++) s=s+2*a[i];
g<<s;
return 0;
}