Cod sursa(job #174993)

Utilizator portocalaDiculescu Elena Alexandra portocala Data 9 aprilie 2008 14:10:35
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.32 kb
Raporteaza aceasta sursa 
#include<fstream.h>
#define dim 1000000
long n,v[dim];

int main()
{ifstream f("fractii.in");
f>>n;
f.close();
long i,j,m;
m=n/2;
for(i=1;i<=n;++i)v[i]=i-1;
for(i=2;i<=m;i++)
 for(j=2*i;j<=n;j+=i)
  v[j]-=v[i];
m=0;
for(i=1;i<=n;++i)
 m+=v[i];
ofstream g("fractii.out");
g<<m*2+1<<'\n';
g.close();
return 0;
}