图论入门-并查集

More is better Time Limit: 5000/1000 MS (Java/Others)    Memory Limit: 327680/102400 K (Java/Others) Total Submission(s): 33215    Accepted Submission(s): 11744 Problem Description Mr Wang wants some boys to help him with a project. Because the project is rather complex, the more boys come, the better it will be. Of course there are certain requirements. Mr Wang selected a room big enough to hold the boys. The boy who are not been chosen has to leave the room immediately. There are 10000000 boys in the room numbered from 1 to 10000000 at the very beginning. After Mr Wang's selection any two of them who are still in this room should be friends (direct or indirect), or there is only one boy left. Given all the direct friend-pairs, you should decide the best way.   Input The first line of the input contains an integer n (0 ≤ n ≤ 100 000) - the number of direct friend-pairs. The following n lines each contains a pair of numbers A and B separated by a single space that suggests A and B are direct friends. (A ≠ B, 1 ≤ A, B ≤ 10000000)   Output The output in one line contains exactly one integer equals to the maximum number of boys Mr Wang may keep.   Sample Input 4 1 2 3 4 5 6 1 6 4 1 2 3 4 5 6 7 8   Sample Output 4 2     Hint A and B are friends(direct or indirect), B and C are friends(direct or indirect), then A and C are also friends(indirect). In the first sample {1,2,5,6} is the result. In the second sample {1,2},{3,4},{5,6},{7,8} are four kinds of answers.   题目连接： http://acm.hdu.edu.cn/showproblem.php?pid=1856

 

这个题是个很简单的并查集的题， 关于并查集的博客有很多， 我这里就只放代码， 讲一下操作， 原理的话， 如果有兴趣可以去查一下。 1 #include 2 #include 3 #include 4 #include 5 #include View Code

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