Cod sursa(job #643188)

Utilizator BlaugranasEnal Gemaledin Blaugranas Data 3 decembrie 2011 09:42:27
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.33 kb
Raporteaza aceasta sursa 
#include<cstdio>
#define N 1000001
int n,i,k,x[N];
long long r=1;
int main()
{freopen("fractii.in","r",stdin);
freopen("fractii.out","w",stdout);
scanf("%d",&n);
for(i=1;i<=n;i++)
       x[i]=i;       
for(i=1;i<=n;i++)
for(k=2*i;k<=n;k+=i)
       x[k]-=x[i];
for(i=2;i<=n;i++)
       r=r+2*x[i];
printf("%lld",r);
return 0;}