Cod sursa(job #2114460)
Utilizator | Iacob Radu raduraradu | Data | 25 ianuarie 2018 16:40:50 |
---|---|---|---|
Problema | Fractii | Scor | 0 |
Compilator | cpp | Status | done |
Runda | ichb_10 | Marime | 0.64 kb |
#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int div (int i,int j)
{
int k=1;
while(i%j==0)
{
i/=j;
k*=j;
}
return k*(j-1);
}int n;int phi[1000001];
int main()
{
int sol=1;
f>>n;
for(int i=2;i<=n;i++)
if(!phi[i])
{
phi[i]=i-1;
for(int j=2;i*j<=n;j++)
{
if(!phi[i*j])
phi[i*j]++;
phi[i*j]*=div(j, i);
}
}
for(int i=1;i<=n;i++)
sol+=2*phi[i];
g<<sol;
return 0;
}