(useless) getConvexHull

linear inclusive?

can't just do ccw < 0 because if the polygon is line form some points get included in the hull twice (edge case)

 

upd : now all in Geometry..

Polygon getConvexHull(Polygon poly) {
  std::sort(poly.begin(), poly.end());
  poly.resize(std::unique(poly.begin(), poly.end()) - poly.begin());
  if (int(poly.size()) < 3) {
    return poly;
  }
  Polygon hull;
  for (int tries = 0; tries < 2; ++tries) {
    auto start = hull.size();
    for (const auto& pt : poly) {
      while (hull.size() > start + 1 && ccw(hull[hull.size() - 2], hull.back(), pt) <= 0) {
        hull.pop_back();
      }
      hull.push_back(pt);
    }
    hull.pop_back();
    std::reverse(poly.begin(), poly.end());
  }
  return hull;
}