POJ 1611 The Suspects_the suspects题目时间超限-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_51199197/article/details/109026091

给定学生群体和团体信息，当某学生疑似SARS病例时，找出所有可能的疑似病例。利用并查集数据结构解决此问题。

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The Suspects

Time Limit: 1000MS Memory Limit: 20000K

Description
Severe acute respiratory syndrome (SARS), an atypical pneumonia of unknown aetiology, was recognized as a global threat in mid-March 2003. To minimize transmission to others, the best strategy is to separate the suspects from others.
In the Not-Spreading-Your-Sickness University (NSYSU), there are many student groups. Students in the same group intercommunicate with each other frequently, and a student may join several groups. To prevent the possible transmissions of SARS, the NSYSU collects the member lists of all student groups, and makes the following rule in their standard operation procedure (SOP).
Once a member in a group is a suspect, all members in the group are suspects.
However, they find that it is not easy to identify all the suspects when a student is recognized as a suspect. Your job is to write a program which finds all the suspects.

Input
The input file contains several cases. Each test case begins with two integers n and m in a line, where n is the number of students, and m is the number of groups. You may assume that 0 < n <= 30000 and 0 <= m <= 500. Every student is numbered by a unique integer between 0 and n−1, and initially student 0 is recognized as a suspect in all the cases. This line is followed by m member lists of the groups, one line per group. Each line begins with an integer k by itself representing the number of members in the group. Following the number of members, there are k integers representing the students in this group. All the integers in a line are separated by at least one space.
A case with n = 0 and m = 0 indicates the end of the input, and need not be processed.

Output
For each case, output the number of suspects in one line.

Sample Input

100 4
2 1 2
5 10 13 11 12 14
2 0 1
2 99 2
200 2
1 5
5 1 2 3 4 5
1 0
0 0

Sample Output

4
1
1

题意：

有n个学生，m个团体，一个学生可以属于多个团体，一旦有一个学生是疑似患病，则该团体都疑似患病。题目要求我们找到疑似SARS病毒的携带者人数。

解题思路：

首先我们先看下题目，题目中的意思，假如一个学生是疑似携带者，那么这个学生所在的团体全部都是疑似携带者。当然一个人可以在多个团体中。

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