PAT 1107 Social Clusters

1107. Social Clusters (30)

When register on a social network, you are always asked to specify your hobbies in order to find some potential friends with the same hobbies. A "social cluster" is a set of people who have some of their hobbies in common. You are supposed to find all the clusters.

Input Specification:

Each input file contains one test case. For each test case, the first line contains a positive integer N (<=1000), the total number of people in a social network. Hence the people are numbered from 1 to N. Then N lines follow, each gives the hobby list of a person in the format:

K_i: h_i[1] h_i[2] ... h_i[K_i]

where K_i (>0) is the number of hobbies, and h_i[j] is the index of the j-th hobby, which is an integer in [1, 1000].

Output Specification:

For each case, print in one line the total number of clusters in the network. Then in the second line, print the numbers of people in the clusters in non-increasing order. The numbers must be separated by exactly one space, and there must be no extra space at the end of the line.

Sample Input:

83: 2 7 101: 42: 5 31: 41: 31: 44: 6 8 1 51: 4

Sample Output:

34 3 1

#include <cstdio>#include <algorithm>#include <cstring>#include <iostream>#include <set>using namespace std;int fa[1001];void Init(){for(int i=1;i<=1000;i++){fa[i]=i;}}int Get(int x){return fa[x]=(fa[x]==x?x:Get(fa[x]));}void Merge(int x,int y){int a=Get(x);int b=Get(y);if(a!=b){fa[b]=a;}}int main(){set<int> s[1001];//每个爱好建立一个集合int n,m,num,cnt=0;//cnt为不相交集的个数int book[1001],count[1001];//book 标记出现的爱好 count 儿子计数memset(book,0,sizeof(book));memset(count,0,sizeof(count));Init();cin>>n;for(int i=1;i<=n;i++){cin>>m;getchar();for(int j=1;j<=m;j++){cin>>num;book[num]=1;s[num].insert(i);}}set<int> ::iterator it;for(int i=1;i<=1000;i++){if(book[i]){int x=*(s[i].begin());for(it=++s[i].begin();it!=s[i].end();it++){Merge(x,*it);}}}for(int i=1;i<=n;i++){int x=Get(i);cnt+=!count[x];count[x]++;}sort(count+1,count+n+1);cout<<cnt<<endl;for(int i=n;count[i];i--){cout<<count[i];printf("%c",count[i-1]==0?'\n':' ');}return 0;}

//此题不用集合也能做,如vector

//此题也可以建图，用搜索做，搜索有几个连通分量