Example: Suppose we are given three cities A,B,C, and we are given roads (AB), (AC), (BA), (BB), (CB), (CC). (The first is a road from A to B;etc).

• 注意： 我们并不保证在‘宇宙示路法’中你的朋友将经过深圳，但是她的终点只能，且必须在深圳。