The Suspects
| Time Limit: 1000MS | Memory Limit: 20000K | |
| Total Submissions: 19754 | Accepted: 9576 |
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.
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.
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
Source
并查集
代码：
1 #include<stdio.h> 2 #include<string.h> 3 #define maxn 30000 4 int n,m; 5 int father[maxn],rank[maxn]; 6 void init() 7 { 8 for(int i=0;i<n;i++) 9 { 10 father[i]=i; 11 rank[i]=1; 12 } 13 } 14 int setfind(int x) 15 { 16 if(x!=father[x]) 17 x=setfind(father[x]); 18 return x; 19 20 } 21 void _union(int a,int b) 22 { 23 a=setfind(a); 24 b=setfind(b); 25 if(a!=b) 26 { 27 if(rank[a]<rank[b]) 28 { 29 father[a]=b; 30 rank[b]+=rank[a]; 31 } 32 else 33 { 34 father[b]=a; 35 rank[a]+=rank[b]; 36 } 37 } 38 } 39 int main() 40 { 41 int a,b,c; 42 while(scanf("%d%d",&n,&m),m+n) 43 { 44 init(); 45 while(m--) 46 { 47 scanf("%d %d",&a,&b); 48 while(a>1) 49 { 50 scanf("%d",&c); 51 _union(b,c); 52 b=c; 53 a--; 54 } 55 } 56 printf("%d\n",rank[setfind(0)]); 57 } 58 59 return 0; 60 }