Cod sursa(job #2245044)
Utilizator | Lixandru Andrei lixi | Data | 24 septembrie 2018 17:20:47 |
---|---|---|---|
Problema | Fractii | Scor | 100 |
Compilator | cpp | Status | done |
Runda | Arhiva de probleme | Marime | 0.51 kb |
#include <iostream>
#include<fstream>
#define Nmax 1000001
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int sol[Nmax];
int main()
{
int N;
f >> N;
for(int i = 2; i <= N; i++)
sol[i] = i - 1;
int M=N/2;
for(int i = 2; i <= M; i++)
for(int j = 2 * i; j <= N; j += i)
sol[j] -= sol[i];
long long rez = 0;
for(int i = 2; i <= N; i++)
rez += sol[i];
rez *= 2;
rez += 1;
g << rez;
return 0;
}