Q21 Unibuc fara explicatii

#include <iostream>
#include <set>
using namespace std;
set<long long> S;
long long frecv[4], v[] = {3,4,5,8,10,12,14,32,57,64};
int main()
{
    for(int i = 0;i<(1<<20);i++)
    {
        for(int j = 0;j<4;j++)
            frecv[j] = 0;
        for(int j = 0;j<10;j++)
        {
            int nrelem = ((i >> (2*j)) % 4);
            frecv[nrelem] += v[j];
        }
        long long P = frecv[1] + frecv[2] + frecv[3];
        bool valid = true;
        for(int j = 0; j < 3 && valid; j++)
        {
            if(P - 2 * frecv[j + 1] <= 0)
                valid = false;
            if(frecv[j % 3 + 1] >= frecv[(j+1) % 3 + 1] + frecv[(j+2) % 3 + 1])
                valid = false;
        }
        if(valid)
        {
           long long aria = P * (P - 2*frecv[1]) * (P - 2*frecv[2]) * (P - 2*frecv[3]);
           S.insert(aria);
        }

    }
    cout << S.size() << '\n';
    return 0;
}