Cod sursa(job #370967)

Utilizator SzabiVajda Szabolcs Szabi Data 2 decembrie 2009 20:56:24
Problema Fractii Scor 30
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.34 kb
Raporteaza aceasta sursa 
#include <stdio.h>
long phi[1000005];

int main(){
long i,j,sum=0,n;
freopen("fractii.in","r",stdin);
freopen("fractii.out","w",stdout);
scanf("%ld",&n);

for(i=1;i<=n;i++){
phi[i]=i-1;}
for(i=2;i<=n;i++){
for(j=2*i;j<=n;j+=i){
 phi[j]-=phi[i];
}
}

for(i=2;i<=n;i++){
 sum+=phi[i];
}

printf("%ld\n",2*sum+1);
 return 0;
}