There are an interesting problem https://community.topcoder.com/stat?c=problem_statement&pm=2384&rd=4755

Here is the tutorial https://www.topcoder.com/community/data-science/data-science-tutorials/geometry-concepts-using-geometry-in-topcoder-problems/

I cant understand the line “the test point is on the interior if, and only if, the ray crosses the boundary an odd number of times.”

why odd number of time when the polygon vertices are in even number ?

It will be a greate help if u explain it to me . Thanks in advance