天梯赛L3 社交集群

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题目链接：点击打开链接

思路：并查集

#include <bits/stdc++.h>
using namespace std;
map<int,int> m;
vector<int> v;
int fa[1005];
int find(int x){
	return fa[x] = (fa[x] == x?x:find(fa[x]));
} 
void merge(int x,int y){
	int a = find(x);
	int b = find(y);
	if(a == b) return;
	fa[a] = b;
}
int main(){
	int n;
	scanf("%d",&n);
	for(int i = 1;i <= 1000;i++){
		fa[i] = i;
	}
	m.clear();
	v.clear();
	for(int i = 1;i <= n;i++){
		int k,root,son;
		char ch;
		cin >> k;
		ch = getchar();
		cin >> root;
		v.push_back(root);
		for(int j = 1;j < k;j++){
			cin >> son;
			merge(son,root);
		}
	}
	for(int i = 0;i < v.size();i++){
		int x = find(v[i]);
		m[x]++;
	}
	v.clear();
	for(int i = 1;i <= 1000;i++){
		if(m.find(i) != m.end()){
			v.push_back(m[i]);
		}
	}
	cout << v.size() <<endl;
	sort(v.begin(),v.end(),greater<int>());
	for(int i = 0;i < v.size();i++){
		printf("%d%c",v[i],i == v.size() - 1?'\n':' ');
	}
	return 0;
}