Walk with a green wall to your right, and a blue or white wall to your left. It's a long path, but shouldn't be too hard to see? I remember being amused that P

Walk with a green wall to your right, and a blue or white wall to your left. It's a long path, but shouldn't be too hard to see? I remember being amused that Paint's flood fill could be used to solve mazes. It shows that flood fill is, worst case, as hard as solving a maze, so it needs to do something like DFS or BFS.