灯塔(LightHouse) Description As shown in the following figure, If another lighthouse is in gray area, they can beacon each other. For example, in following figure, (B, R) is a pair of lighthous
灯塔(LightHouse) Description As shown in the following figure, If another lighthouse is in gray area, they can beacon each other. For example, in following figure, (B, R) is a pair of lighthouse