Lighthouse Light Propagation

Simulate light propagation across a 2-D matrix: lighthouses emit light in defined directions, and walls or grid edges stop each ray. The core mechanic is ray casting or directional traversal; exact direction encoding is intentionally left for clarification. Requirements A 2-D grid contains lighthouse cells. Each lighthouse emits beams in one or more directions. A beam travels in a straight line until it reaches a wall or leaves the grid. Return the cells that receive light. Clarify the direction encoding and whether any reflection, rotation, or corner interaction exists. Notes Ray casting walks each lighthouse-direction pair cell by cell, marking lit cells until blocked. A directional traversal instead stores (cell, direction) states; both are straightforward when beams do not branch. Deduplicate repeated (cell, direction) states if beams can merge or cycle. If rotation adds a time phase, extend the state with that phase. State no-reflection and wall-inclusion assumptions before coding when the contract does not define them. Preparation Implement a direction-vector ray helper and test boundary and wall stops. Practice directional traversal with (row, col, direction) states and a visited set. Prepare clarification questions for direction encoding, source-cell lighting, wall cells, reflection, and rotation.