1107. Social Clusters (30)并查集

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<map>#include<cstdio>#include<algorithm>using namespace std;int father[1001];int find(int x){    if (x==father[x]) return x;    return father[x]=find(father[x]);}bool cmp(int a,int b){    return a>b;}int a[1005],out[1005],index1=0;int n;map<int ,int > ma;int main(){    cin>>n;    for (int i=1;i<=1000;i++)    {        father[i]=i;    }    for(int i=1;i<=n;i++)    {        int sum,temp;        scanf("%d: ",&sum);        scanf("%d",&temp);        a[i]=temp;        temp=find(temp);        for (int j=1;j<sum;j++)        {            int nu;            scanf("%d",&nu);            nu=find(nu);            father[nu]=temp;        }    }    for(int i=1;i<=n;i++)    {        ma[find(a[i])]++;    }    for (map<int ,int > ::iterator it=ma.begin();it!=ma.end();it++)    {        out[index1++]=it->second;    }    sort(out,out+index1,cmp);    cout<<index1<<endl;    for (int i=0;i<index1;i++)    {        cout<<out[i];        if (i!=index1-1)        {            cout<<" ";        }    }    return 0;}