Cod sursa(job #3272520)

Utilizator unomMirel Costel unom Data 29 ianuarie 2025 18:25:36
Problema Pairs Scor 0
Compilator cpp-64 Status done
Runda Arhiva de probleme Marime 1.27 kb
#include <fstream>

using namespace std;

ifstream in("pairs.in");
ofstream out("pairs.out");
int n, ans, scz;
int v[100005];
int frec[1000005];

int main()
{
    in>>n;
    for(int i = 1; i<=n; i++)
    {
        in>>v[i];

        frec[v[i]]++;
    }

    ans = (n * (n - 1)) / 2;

    for(int i = 2; i<=1000000; i++)
    {
        int x = i;
        int cnt = 0;
        int ok = 1;

        for(int d = 2; d*d<=x; d++)
        {
            if(x % d == 0)
            {
                cnt++;

                int put = 0;
                while(x % d == 0)
                {
                    x /= d;
                    put++;
                }

                if(put > 1)
                {
                    ok = 0;
                    break;
                }
            }
        }

        if(x > 1)
        {
            cnt++;
        }

        if(ok == 0)
        {
            continue;
        }

        int nr = 0;
        for(int j = 1; i * j <= 1000000; j++)
        {
            nr += frec[i * j];
        }

        if(cnt % 2 == 1)
        {
            scz += nr;
        }
        else
        {
            scz -= nr;
        }
    }

    ans -= scz;

    out<<ans;

    return 0;
}