1.问题描述
若用无向图来表示高速公路网，其中顶点表示城市，边表示城市之间的高速公路，试设计一个找路程序，获取两个城市之间的所有简单路径。
2.输入数据
输入结点个数n，输入城市的编号，由于是四位数字，为了简便统一起见，设置为int类型，通过输入两个城市的编号表示这两个城市之间有高速公路。最后找路的时候输入两个城市的编号，表示该路的起点和终点。
3.输出数据
输出由城市编号组成的所有可能路径，类型为int型。(1. problem descr iption
If we use undirected graph to express expressway network, where vertices represent cities and express expressways between cities, we try to design a road finding program to get all the simple paths between two cities.
2. input data
The number of input nodes n, enter the number of the city, because it is four digit number, for the sake of simplicity and uniformity, it is set to int type. By entering the number of the two cities, there is a highway between the two cities. Finally, when looking for the road, enter the number of the two cities to indicate the starting point and the end point of the road.
3. output data
Output all possible paths composed of city numbers, type int.)