Cod sursa(job #629251)

Utilizator thesvcoolmanLucian Bicsi thesvcoolman Data 2 noiembrie 2011 23:02:47
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 long a[1000100],n,s=1;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int main() {
	int i,j;

	fin>>n;
	for(i=1;i<=n;i++)
		a[i]=i-1;
	for(i=2;i<=n;i++)
		for(j=i*2;j<=n;j=j+i)
			a[j]=a[j]-a[i];
	for(i=1;i<=n;i++)
		s=s+2*a[i];
	fout<<s;
	return 0;
}