Cod sursa(job #2368602)

Utilizator alexandruilieAlex Ilie alexandruilie Data 5 martie 2019 16:43:45
Problema Fractii Scor 100
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
#include <fstream>

using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int N,i,j,v[1000005];
long long nr;
int main()
{
    f>>N;
    for(i=2;i<=N;i++)
        v[i]=i-1;
    for(i=2;i<=N/2;i++)
        for(j=2*i;j<=N;j+=i)
        v[j]-=v[i];
    for(i=2;i<=N;i++) nr+=v[i];
    g<<2*nr+1;
    return 0;
}