Cod sursa(job #3258532)

Utilizator brianabucur11Briana Bucur brianabucur11 Data 23 noiembrie 2024 00:58:52
Problema Pairs Scor 50
Compilator cpp-64 Status done
Runda cex_3 Marime 0.55 kb
#include <bits/stdc++.h>

using namespace std;

ifstream fin ("pairs.in");
ofstream fout ("pairs.out");

const int NMAX=1e6+5;
int n, Max, v[NMAX], fr[NMAX];

int main()
{
    fin >> n;
    for (int i=1; i<=n; i++)
    {
        int x;
        fin >> x;
        fr[x]++;
        Max=max(Max,x);
    }
    for (int i=Max; i>=1; i--)
    {
        for (int j=1; j*i<=Max; j++)
            v[i]+=fr[j*i];
        v[i]=v[i]*(v[i]-1)/2;
        for (int j=2; j*i<=Max; j++)
            v[i]-=v[j*i];
    }
    fout << v[1];
    return 0;
}