Cod sursa(job #459453)
Utilizator | cristescu liviu ms-ninja | Data | 29 mai 2010 19:42:35 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.41 kb |
#include <fstream>
using namespace std;
#define dim 1000000
long v[dim];
int main()
{
long long i, j, n, s=0;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
fin>>n;
long f=0;
for(i=2;i<=n;++i)
{
if(v[i]==0)
{
for(j=i+i;j<=n;j+=i)
{
if(v[j]==0)
v[j]=j-j/i;
else
v[j]=v[j]-v[j]/i;
}
s+=i-1;
}
else
s+=v[i];
}
fout<<2*s+1;
return 0;
}