#include <vector>
#include <algorithm>
#include <iostream>
#include <array>
int main()
{
    const int kDesired = 0;
    std::vector<int> a = { 1, -1, 2, 0, -2, 4, -2, -2, 4 };
    std::sort(a.begin(), a.end());
    std::vector<std::array<int, 3>> triples;
    for (int i = 0; i < (int)a.size(); ++i) {
        const int others = kDesired - a[i];
        for (int j = i + 1; j < (int)a.size(); ++j) {
            for (int k = (int)a.size() - 1; k > j; --k) {
                if (a[j] + a[k] == others) {
                    triples.push_back({ { a[i], a[j], a[k] } });
                }
                else if (a[j] + a[k] < others) {
                    break;
                }
                while (j + 1 < k && k < (int)a.size() && a[k] == a[k - 1]) --k;
            }
            while (i + 1 <= j && j < (int)a.size() - 1 && a[j] == a[j + 1]) ++j;
        }
        while (0 <= i && i < (int)a.size() - 1 && a[i] == a[i + 1]) ++i;
    }
    for (const auto& t : triples) {
        std::cout << t[0] << " " << t[1] << " " << t[2] << std::endl;
    }
    return 0;
}