Cod sursa(job #1293115)
Utilizator | Ungureanu Adrian vladia13 | Data | 15 decembrie 2014 13:04:28 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.48 kb |
#include <iostream>
#include<fstream>
#include<cmath>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int p[1000001];
int main()
{
long long n,s=0,i,j;
f >> n;
for(i = 1; i <= n; i++)
p[i] = i - 1;
for(i = 2; i <= n; i++)
for(j = i + i; j <= n; j += i)
p[j] -= p[i];
for(i = 1; i <= n; i++)
s = s + p[i];
g << 2*s + 1;
f.close();
g.close();
return 0;
}