1013 Battle Over Cities (25)（25 分）

最新推荐文章于 2022-11-22 19:07:26 发布

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最新推荐文章于 2022-11-22 19:07:26 发布 · 2.9k 阅读

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#PAT #甲级 #C++

该博客讨论了PAT甲级考试中的一道编程题，涉及图论和连通性问题。当一个城市被占领时，需要计算需要修复多少条高速公路以保持其余城市的连接。博主通过深度优先搜索策略解决问题，并强调了在C++中使用printf和scanf比cout和cin在性能上的优势，尤其是在处理大量输入输出时。文章还给出了AC代码解决方案。

1 题目
2 解题思路
3 AC代码

1 题目

　　It is vitally important to have all the cities connected by highways in a war. If a city is occupied by the enemy, all the highways from/toward that city are closed. We must know immediately if we need to repair any other highways to keep the rest of the cities connected. Given the map of cities which have all the remaining highways marked, you are supposed to tell the number of highways need to be repaired, quickly.
　　For example, if we have 3 cities and 2 highways connecting city~1~-city~2~ and city~1~-city~3~. Then if city~1~ is occupied by the enemy, we must have 1 highway repaired, that is the highway city~2~-city~3~.

Input

　　Each input file contains one test case. Each case starts with a line containing 3 numbers N (&lt1000), M and K, which are the total number of cities, the number of remaining highways, and the number of cities to be checked, respectively. Then M lines follow, each describes a highway by 2 integers, which are the numbers of the cities the highway connects. The cities are numbered from 1 to N. Finally there is a line containing K numbers, which represent the cities we concern.

Output