Cod sursa(job #2204629)

Utilizator triscacezarTrisca Vicol Cezar triscacezar Data 16 mai 2018 18:48:51
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.33 kb
Raporteaza aceasta sursa 
#include <bits/stdc++.h>

using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int i,j,n,a[1000010];
long long ans;
int main()
{
    f>>n;
    for(i=1;i<=n;i++)
    {
        a[i]+=i;
        for(j=i*2;j<=n;j+=i)
            a[j]-=a[i];
        ans+=a[i];
    }
    g<<2*ans-1;

    return 0;
}