1107 Social Clusters (30 分)

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 (≤), 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​​ (>) is the number of hobbies, and [ 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:

8
3: 2 7 10
1: 4
2: 5 3
1: 4
1: 3
1: 4
4: 6 8 1 5
1: 4

 

Sample Output:

3
4 3 1

#include<bits/stdc++.h>
using namespace std;
const int maxn=1010;
int hobbies[maxn];
int father[maxn];
int isRoot[maxn];
bool cmp(int a,int b){
    return a>b;
}
int findFather(int x){
    int a=x;
    while(x!=father[x]){
        x=father[x];
    }
    while(a!=father[a]){
        int z=a;
        a=father[a];
        father[z]=x;
    }
    return x;
}
void Union(int a,int b){
    int x=findFather(a);
    int y=findFather(b);
    if(x!=y){
        father[x]=y;
    }
}

int main(){
    int n,m,id,temp;
    scanf("%d",&n);
    for(int i=1;i<maxn;i++){
        father[i]=i;
    }
    for(int i=1;i<=n;i++){
        scanf("%d: ",&m);
        for(int j=0;j<m;j++){
            scanf("%d",&temp);
            if(hobbies[temp]==0){
                hobbies[temp]=i;//是谁的爱好
            }
            Union(i,hobbies[temp]);//相同爱好的人，放在一块；而不是把相同的爱好放在一块
        }
    }
    for(int i=1;i<=n;i++){
        isRoot[findFather(i)]++;
    }
    int numRoot=0;
    for(int i=1;i<=n;i++){
        if(isRoot[i]!=0){
            numRoot++;
        }
    }
    printf("%d\n",numRoot);
    sort(isRoot,isRoot+n+1,cmp);
    for(int i=0;i<numRoot;i++){
        if(i<numRoot-1){
            printf("%d ",isRoot[i]);
        }
        else{
            printf("%d\n",isRoot[i]);
        }
        
    }
    return 0;
}