Cod sursa(job #3258513)

Utilizator Ruxandra009Ruxandra Vasilescu Ruxandra009 Data 22 noiembrie 2024 22:59:45
Problema Pairs Scor 50
Compilator cpp-64 Status done
Runda cex_3 Marime 0.6 kb
#include <fstream>
#include <vector>

using namespace std;

ifstream f("pairs.in");
ofstream g("pairs.out");

const int nmax = 1000005;
int fr[nmax], maxi, n, ans[nmax];

int main()
{
    f >> n;
    for(int i = 1; i <= n; i ++)
    {
        int x; f >> x;
        fr[x] ++; maxi = max(maxi, x);
    }

    for(int i = maxi; i >= 1; i --)
    {
        for(int j = i; j <= maxi; j += i)
            ans[i] += fr[j];

        ans[i] = (ans[i] + 1) * ans[i] / 2;

        for(int j = 2 * i; j <= maxi; j += i)
            ans[i] -= ans[j];
    }

    g << ans[1];
    return 0;
}