Cod sursa(job #830085)
Utilizator | Stefanescu Mihai-Nicolae Stefanescu_Mihai | Data | 6 decembrie 2012 13:06:18 |
---|---|---|---|
Problema | Fractii | Scor | 0 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.39 kb |
#include<fstream>
using namespace std;
unsigned int c,i,phi[1000002],p,n;
int ph(int a)
{
for (i=2;i<=a;i++)
phi[i]=i-1;
for (i=2;i<=a;i++)
for (int c=2*i;c<=n;c+=i)
phi[c] -= phi[i];
p+=phi[i];
return p;
}
int main()
{
unsigned int m=0;
ifstream f1("fractii.in");
f1>>n;
ofstream f2("fractii.out");
for (i=2;i<=n;i++)
m=m+ph(i);
f2<<2*m+1;
return 0;
}