Cod sursa(job #579586)

Utilizator ionutpPala Ionut ionutp Data 12 aprilie 2011 11:52:55
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.32 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
long a[1000100],n,i,j;
long long suma;
int main()
{fin>>n;;
	for(i=1;i<=n;i++)
		a[i]=i;
	for(i=2;i<=n;i++)
		if(a[i]==i)
			for(j=i;j<=n;j+=i)
				a[j]=a[j]/i*(i-1);
	for(i=2;i<=n;++i)
		suma=suma+a[i];
	fout<<2*suma+1;
	return 0;
}