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Good luck and have fun!

Say yo want a set of points sorted in some counterclockwise order. What is the best (fast, precise, short) way to do it? The atan2l function is precise and short but way too slow.

Update: One of the previous entries were wrong. I like the following one which hopefully works.

inline bool up (point p) {
  return p.y > 0 or (p.y == 0 and p.x >= 0);
}

sort(v.begin(), v.end(), [] (point a, point b) {
  return up(a) == up(b) ? a.x * b.y > a.y * b.x : up(a) < up(b);
});