Cod sursa(job #2617796)

Utilizator Gliumarin negai Gliu Data 22 mai 2020 21:43:35
Problema Fractii Scor 30
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 0.36 kb
Raporteaza aceasta sursa 
#include <iostream>
#include <fstream>

using namespace std;

ifstream in("fractii.in");
ofstream out("fractii.out");

const int nmax=1000000;
int n,ans=0,d[nmax];

int main(){

in >>n;

for(int i=2;i<=n;i++)
   d[i]=i-1;
   
for(int i=2;i<=n;i++){
	ans+=d[i];
	
	for(int j=2*i;j<=n;j+=i)
		d[j]-=d[i];	
}
out <<2 * ans +1;
return 0;
}