Cod sursa(job #415037)

Utilizator ClasianMunteanu Petre Clasian Data 10 martie 2010 20:52:54
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.32 kb
Raporteaza aceasta sursa 
#include<fstream.h>
ifstream f("fractii.in");
ofstream g("fractii.out");
int n,fs[1000002],i,j;
long long rez;
int main()
{   f>>n;
	for(i=1;i<=n;++i)
	fs[i]=i-1;
	rez=1;
	for(i=2;i<=n;++i)
	{
		rez+=fs[i];
		for(j=i+i;j<=n;j+=i)
		fs[j]-=fs[i];
	}
    g<<(rez<<1)-1;
	f.close();
	g.close();
	return 0;
}