Hi, thanks for the pull request! But I'm a bit confused, so you mean that the current implementation is incorrect? Is it possible for you to also add a fix for it in such a case?

Visit the preview URL for this PR (for commit 922cb9b):

https://cp-algorithms--preview-1258-sdg06vwe.web.app

(expires 2024-04-24T21:46:51.216932235Z)

Yes, I believe there is an error. Unfortunately I do not have the time right now create a fix in cpp. I am coding in Python and managed to create a workaround, but I am not even sure it is correct. All I can provide right now is the comment I have added to my code 2 weeks ago:

The sourced algorithm contains an error when finding the outer face. It cannot be just found by checking the orientation
of the vertices. Therefore, I changed the logic.
First we find the outer face candidates - these are the faces containing all the vertices.
The outer face is then the face with the least vertices.
Proof by dispute:
The face with more vertices f1 must contain at least one extra vertex v.
This vertex lies inside the face with fewer vertices f2.
If we create a new face f3 by splitting any edge (a,b) of the f2 into (a,v)&(v,b),
then the edge (a,b) won't lie in the new face f3.
Therefore, the extra vertex v is not a part of the outer face.
Repeat for all extra vertices.

Preview the changes for PR #1258 at https://gh.cp-algorithms.com/1258/ (current version: c7a8dd7).

Allegedly fixed in #1394.