Cod sursa(job #2784504)

Utilizator BlaugranasEnal Gemaledin Blaugranas Data 16 octombrie 2021 16:26:23
Problema Fractii Scor 100
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 0.31 kb
Raporteaza aceasta sursa 
#include<fstream>
using namespace std;
int n,i,k,x[1000001];
long long r=1;
int main()
{
	ifstream("fractii.in")>>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+=2*x[i];
	ofstream("fractii.out")<<r;
	return 0;
}