Cod sursa(job #3138943)
Utilizator | Data | 23 iunie 2023 15:21:17 | |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp-64 | Status | done |
Runda | Arhiva de probleme | Marime | 0.5 kb |
#include <fstream>
#define NMAX 1000000
using namespace std;
ifstream cin("fractii.in");
ofstream cout("fractii.out");
int n,phi[NMAX+1],i,j;
long long nr;
int main()
{
cin>>n;
nr=1;
for(i=1; i<=n; i++)
phi[i]=i;
for(i=2; i<=n; i++)
if(phi[i]==i)
{
phi[i]--;
for(j=2; j*i<=n; j++)
phi[j*i]=phi[j*i]/i*(i-1);
}
for(i=2; i<=n; i++)
{
nr=nr+phi[i]*2;
}
cout<<nr;
return 0;
}