Cod sursa(job #443861)
Utilizator | Dobos Ionut wamfever | Data | 18 aprilie 2010 18:03:57 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.55 kb |
#include<fstream>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n, i, j;
int a[1000000];
long long nr;
void genereaza()
{ fin>>n;
for(i=2;i<=n;i++) a[i] = i-1;
}
void rezolva()
{ nr=1;
for(i=2;i<=n;i++)
{
nr+=2*a[i];
for(j=2*i;j<=n;j+=i)
a[j]-=a[i];
}
fout << nr;
fin.close();
fout.close();
}
int main()
{
genereaza();
rezolva();
return 0;
}