Cod sursa(job #1194686)

Utilizator gbibBacotiu Gabi gbib Data 4 iunie 2014 16:49:06
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
#include <fstream>

using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int phi[1000005];
int main()
{int n,i,j;
long long s=0;
in>>n;
for(i=2;i<=n;++i)
    phi[i]=i-1;
for(i=2;i<=n;++i)
    for(j=2*i;j<=n;j+=i)
        phi[j]-=phi[i];
for(i=2;i<=n;i++)
    s=s+phi[i];
out<<2*s+1;

    return 0;
}