Cod sursa(job #2421488)

Utilizator lucaperjuLuca Perju Verzotti lucaperju Data 15 mai 2019 10:50:51
Problema Fractii Scor 0
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 0.35 kb
#include <fstream>

using namespace std;
ifstream cin ("fractii.in");
ofstream cout ("fractii.out");
int phi[1000003];
int main()
{
    int n,i,j;
    cin>>n;
    for(i=1;i<=n;++i)
        phi[i]=i-1;
    for(i=2;i<=n;++i)
        for(j=i*2;j<=n;j+=i)
            phi[j]-=phi[i];
    int s=0;
    for(i=1;i<=n;++i)
        s+=phi[i];
    cout<<s;
    return 0;
}