https://www.cnblogs.com/vectors07/p/8053427.html
I.e., a n-gon (n> = 3) is cut along the vertex, divided into triangles, up to how many kinds of programs
https://www.cnblogs.com/vectors07/p/8053427.html
I.e., a n-gon (n> = 3) is cut along the vertex, divided into triangles, up to how many kinds of programs