Cod sursa(job #1977470)

Utilizator georgerapeanuRapeanu George georgerapeanu Data 5 mai 2017 12:00:28
Problema Fractii Scor 100
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.31 kb
Raporteaza aceasta sursa 
#include <cstdio>
using namespace std;
FILE *f=fopen("fractii.in","r");
FILE *g=fopen("fractii.out","w");
int N,F[1000005];long long r=0;int main(){fscanf(f,"%d",&N);for(int i=1;i<=N;i++){F[i]=i;}for(int i=2;i<=N;i++){if(F[i]==i){for(int j=i;j<=N;j+=i)F[j]=(F[j]/i)*(i-1);}r+=F[i];}fprintf(g,"%lld",2*r+1);return 0;}