Cod sursa(job #1822340)
Utilizator | Data | 4 decembrie 2016 19:28:36 | |
---|---|---|---|
Problema | Fractii | Scor | 30 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.45 kb |
#include <bits/stdc++.h>
#define nmax 1000001
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int phi[nmax];
int main()
{
int x,n;
int nr=0;
fin>>n;
for(int i=1;i<=n;i++)
phi[i]=i-1;
for(int i=2;i<=n;i++)
{
x=phi[i];
for(int j=2*i;j<=n;j+=i)
{
phi[j]=phi[j]-x;
}
nr+=x;
}
fout<<2*nr+1;
return 0;
}