poj 1611 The Suspects

The Suspects

Time Limit: 1000MS Memory Limit: 20000KTotal Submissions: 33396 Accepted: 16201

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 42 1 25 10 13 11 12 142 0 12 99 2200 21 55 1 2 3 4 51 00 0

Sample Output

411

Source

Asia Kaohsiung 2003

提示

题意：

严重急性呼吸综合征（非典型性肺炎），一种未知病因的非典型性肺炎，被确认为2003月中旬的一个全球性威胁。为了最大限度地减少传染给别人，最好的策略是把病人和其他人分开。在中山大学，有很多学生群体。在同一群体的学生相互联系频繁，一个学生可以加入多个群体。为防止“非典”的传染，收集所有学生团体的成员列表。一旦组中的成员有一个病人，该组中的所有成员都是病人。然而，这不容易找出所有的病人。你的工作是写一个程序，求出病人的个数。（假设编号为0的学生是病源）

思路：

并查集入门，记得做数量的统计。

示例程序

Source CodeProblem: 1611Code Length: 1249BMemory: 592KTime: 16MSLanguage: GCCResult: Accepted#include <stdio.h>#include <string.h>int main(){    int n,m,k,i,i1,x,y,a[30000],b[30000];    scanf("%d %d",&n,&m);    while(n!=0)    {        for(i=0;n>i;i++)        {            a[i]=i;            b[i]=1;        }        for(i=1;m>=i;i++)        {            scanf("%d",&k);            for(i1=1;k>=i1;i1++)            {                if(i1==1)                {                    scanf("%d",&x);                }                else                {                    scanf("%d",&y);                    while(x!=a[x])                    {                        x=a[x];                    }                    while(y!=a[y])                    {                        y=a[y];                    }                    if(x==y)//注意相同组的情况                    {                        continue;                    }                    if(y==0)                    {                        a[x]=y;                        b[y]=b[y]+b[x];                    }                    else                    {                        a[y]=x;                        b[x]=b[x]+b[y];                    }                }            }        }        printf("%d\n",b[0]);        scanf("%d %d",&n,&m);    }    return 0;}