Educational Codeforces Round 65 (Rated for Div. 2) C. News Distribution

链接：https://codeforces.com/contest/1167/problem/C

题意：

In some social network, there are nn users communicating with each other in mm groups of friends. Let's analyze the process of distributing some news between users.

Initially, some user xx receives the news from some source. Then he or she sends the news to his or her friends (two users are friends if there is at least one group such that both of them belong to this group). Friends continue sending the news to their friends, and so on. The process ends when there is no pair of friends such that one of them knows the news, and another one doesn't know.

For each user xx you have to determine what is the number of users that will know the news if initially only user xx starts distributing it.

思路：

裸并查集

代码：

#include <bits/stdc++.h>
using namespace std;

const int MAXN = 5e5+10;

int Fa[MAXN];
int Dis[MAXN];

int GetF(int x)
{
    if (Fa[x] == x)
        return Fa[x];
    Fa[x] = GetF(Fa[x]);
    return Fa[x];
}

int main()
{
    int n, m;
    cin >> n >> m;
    for (int i = 1;i <= n;i++)
        Fa[i] = i;
    int num, p;
    for (int i = 1;i <= m;i++)
    {
        cin >> num;
        int head;
        if (num > 0)
        {
            cin >> p;
            head = GetF(p);
            num--;
        }
        while (num--)
        {
            cin >> p;
            int h = GetF(p);
            Fa[h] = head;
        }
    }
    for (int i = 1;i <= n;i++)
    {
        int head = GetF(i);
        Dis[head]++;
    }
    for (int i = 1;i <= n;i++)
    {
        int head = GetF(i);
        cout << Dis[head] << ' ' ;
    }
    cout << endl;

    return 0;
}