Cod sursa(job #2532764)

Utilizator EdgeLordXDOvidiuPita EdgeLordXD Data 28 ianuarie 2020 12:21:18
Problema Fractii Scor 0
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 0.32 kb
Raporteaza aceasta sursa 
#include <iostream>
using namespace std;
int f[1000006];
int main(){
    int n,i,j;
    long long s=0;
    cin>>n;
    for(i=2; i<=n; ++i){
        if(!f[i]){
            for(j=i; j<=n; j+=i){
                f[j]+=j/i-1;
            }
        }
        s+=2LL*(i-f[i]-1);
    }
    cout<<s;
    return 0;
}