This is not a problem from any online judge, but for a project I am working on.

There is an ellipse and a list of points. The task is to score the list with a number between $$$0$$$ and $$$1$$$. A score of $$$1$$$ means that the list of points forms a perfect ellipse. A list forms a perfect ellipse when:

All the points in the list lie on the circumference of the ellipse.

The points are evenly spaced (distributed evenly) across the circumference.

**Formal-ish statement**

The expected time complexity is less than $$$O(N^3)$$$, not strictly necessary. Here, $$$N$$$ is the number of points in the list.

If you want some inspiration, I have attempted the same problem but checked matching with circles and polygons. Demonstration for the circle:

**How it works**