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HDU 1102 Constructing Roads
阅读量:129 次
发布时间:2019-02-27

本文共 3449 字,大约阅读时间需要 11 分钟。

Constructing Roads

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/32768 K (Java/Others)

Total Submission(s): 1914    Accepted Submission(s): 628

Problem Description
There are N villages, which are numbered from 1 to N, and you should build some roads such that every two villages can connect to each other. We say two village A and B are connected, if and only if there is a road between A and B, or there exists a village C such that there is a road between A and C, and C and B are connected.
We know that there are already some roads between some villages and your job is the build some roads such that all the villages are connect and the length of all the roads built is minimum.
 

 

Input
The first line is an integer N (3 <= N <= 100), which is the number of villages. Then come N lines, the i-th of which contains N integers, and the j-th of these N integers is the distance (the distance should be an integer within [1, 1000]) between village i and village j.
Then there is an integer Q (0 <= Q <= N * (N + 1) / 2). Then come Q lines, each line contains two integers a and b (1 <= a < b <= N), which means the road between village a and village b has been built.
 

 

Output
You should output a line contains an integer, which is the length of all the roads to be built such that all the villages are connected, and this value is minimum.
 

 

Sample Input
30 990 692990 0 179692 179 011 2
 

 

Sample Output
179
 

 

 解题:
        还是用克鲁斯卡尔算法。题目大意是:有N个村庄,给定我们每个村庄之间的距离,而两个村庄可以间接相连。然后告诉我们原本有几个村庄已经相连有路相通。要让我们求还要建多长的路,最小的。可以用最小生成树,先把给定的已相连的村庄之间的权值赋为0,其余跟求最小生成树一样。

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