Cod sursa(job #2106540)

Utilizator rares_ciocieaRares Andrei Ciociea rares_ciociea Data 15 ianuarie 2018 21:36:39
Problema Pairs Scor 0
Compilator cpp Status done
Runda Arhiva de probleme Marime 0.58 kb
#include <fstream>

using namespace std;
ifstream in("pairs.in");
ofstream out("pairs.out");
int frecv[1000010],v[100010];
int main()
{
    unsigned long long n,nr,cnt=0,i,max=0,fin=0;
    in>>n;
    for(i=1; i<=n; i++)
    {
        in>>v[i];
        nr=v[i];
        frecv[v[i]]++;
        if(max<v[i])
            max=v[i];
    }
    for(i=2; i<=max; i++)
    {
        nr=i;
        cnt=0;
        while(nr<=max)
        {
            cnt+=frecv[nr];
            nr+=i;
        }
        fin+=cnt*(cnt-1)/2;
    }
    out<<n*(n-1)/2-fin;
   return 0;
}