click 1 to create a wall and click 2 to create grass, then click somewhere to start a bfs search out from that position, then click anywhere on the map to follow the arrows to the start position then click space to edit the map or create a new bfs search. the reason this is useful is because you can find the path from one point to all points on the map, and just follow the arrows to get a path, this means that you could quickly find a path for 100 units to one point easily.
