Cod sursa(job #402398)

Utilizator de3de3Ilinca Diana Andreea de3de3 Data 23 februarie 2010 20:37:54
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");
long tot[1000001];
long n, i, j;
long long nr;
int main(){
	f>>n;
    for(i=2;i<=n;i++)
		tot[i]=i-1;
	for(i=2;i<=n;i++){
		nr+=tot[i];
		for(j=i*2;j<=n;j+=i)
			tot[j]-=tot[i];
	}
	g<<2*nr+1;
	f.close();
	g.close();
	return 0;
}