Geometry

Geometry problems are quite niche and I have really only ever encountered a small handful of them myself. Advent of Code 2023 was where I developed these pointers

Techniques

Check if point is inside polygon

Otherwise known to be raycasting, crossing number algorithm, or the even-odd rule algorithm

• From point $(x, y)$, draw a line infinitely long in 1 direction and check how many sides of the polygon it intersects

  • If intersect odd number of points, inside polygon

  • Otherwise, outside of polygon

• Ensure to check for corner pieces such as L and 7 pieces and do not count those