Cod sursa(job #292574)

Utilizator skatesZaharescu Dragos skates Data 31 martie 2009 11:59:42
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.35 kb
Raporteaza aceasta sursa 
#include<iostream.h>
#include<fstream.h>
#define DMAX 1000000

long w[DMAX+1];
long n,i,s=1,j;
ifstream f("fractii.in");
ofstream g("fractii.out");

int main()
{f>>n;
 for(i=1; i<=n; i++) w[i]=i-1;
 for(i=2; i<=n; i++)
  for(j=2*i; j<=n; j+=i) w[j]-=w[i];
 for(i=1; i<=n; i++)
  s+=2*w[i];
 g<<s<<'\n';
 f.close(); g.close();
 return 0;
}