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:
Ki: hi[1] hi[2] ... hi[Ki] where K​i(>0) is the number of hobbies, and hi[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.

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

3
4 3 1

## 解答

#include<iostream>
#include<unordered_map>
#include<vector>
#include<algorithm>

using namespace std;

unordered_map<int, int> parent;

int Find(int x)
{
// 如果x未在parent中出现过，要初始化
if (parent.find(x) == parent.end()) parent[x] = x;
if (parent[x] == x) return x;
return parent[x] = Find(parent[x]);
}

void Union(int x, int y)
{
int p1 = Find(x), p2 = Find(y);
if (p1 != p2) parent[p1] = p2;
}

int main()
{
int n, m, hobby, tmp;
scanf("%d", &n);
vector<int> people(n), ans;
unordered_map<int, int> cnt;
for (int i = 0; i < n; i++) {
scanf("%d: %d", &m, &tmp);
people[i] = tmp;
for (int j = 1; j < m; j++) {
scanf("%d", &hobby);
Union(tmp, hobby);
}
}
for (int i = 0; i < n; i++) cnt[Find(people[i])]++;
for (auto it = cnt.begin(); it != cnt.end(); it++) ans.push_back(it->second);
sort(ans.begin(), ans.end(), greater<int>());
printf("%lu\n%d", ans.size(), *ans.begin());
for (auto it = ans.begin() + 1; it != ans.end(); it++) printf(" %d", *it);
return 0;
}