1107 Social Clusters （30 分）并查集

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 (≤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:

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<iostream>
#include<vector>
#include<algorithm>
using namespace std;
int hobbies[1001],father[1001],isRoot[1001];

void init()
{
    for(int i=1;i<1001;i++)
        father[i]=i;
}
int findFather(int x)
{
    int a=x;
    while(x!=father[x]) x=father[x];
    //路径压缩
    while(a!=father[a])
    {
        int z=a;
        a=father[a];
        father[z]=x;
    }
    return x;
}

void Union(int a,int b)
{
    int fa=findFather(a);
    int fb=findFather(b);
    if(fa!=fb)
        father[fa]=fb;
}










int main()
{
    int n;
    scanf("%d",&n);
    init();
    for(int i=1;i<n+1;i++)
    {
        int k;
        scanf("%d:",&k);
        for(int j=0;j<k;j++)
        {
            int t;
            scanf("%d",&t);
            if(hobbies[t]==0)
                hobbies[t]=i;//记录这是谁的爱好
            Union(i,hobbies[t]);
        }
    }
    for(int i=1;i<n+1;i++)
    {
        isRoot[findFather(i)]++;
    }
    int cnt=0;
    for(int i=1;i<n+1;i++)
    {
        if(isRoot[i]!=0)
            cnt++;
    }
    printf("%d\n",cnt);
    sort(isRoot,isRoot+n+1,greater<int>());
    printf("%d",isRoot[0]);
    for(int i=1;i<cnt;i++)
    {
        printf(" %d",isRoot[i]);
    }
    return 0;
}