Cod sursa(job #1150219)
Utilizator | Radu Cebotari radu_cebotari | Data | 22 martie 2014 17:58:49 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.61 kb |
#include<fstream>
#include<iostream>
using namespace std;
int phi[1000020];
void euler(int n)
{
int i,j;
for( i = 1 ; i<=n ; i++)
phi[i] = i-1;
for(i = 2 ; i<= n ; i++)
for( j = 2*i ; j <=n ; j+=i)
phi[j]-=phi[i];
}
long long calculeaza(int n)
{
long long sol = 0;
for(int i = 1 ; i<=n ; i++)
sol+=phi[i];
return sol;
}
int main()
{
ifstream in("fractii.in");
ofstream out("fractii.out");
long long n,k;
in>>n;
euler(n);
k = calculeaza(n);
out<<2*k+1;
in.close();
out.close();
return 0;
}