cf Educational Codeforces Round 65 C. News Distribution

原题:

C. News Distribution
time limit per test
2 seconds
memory limit per test
256 megabytes
input
standard input
output
standard output

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

Initially, some user x 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 x you have to determine what is the number of users that will know the news if initially only user x starts distributing it.

Input

The first line contains two integers n and m (1≤n,m≤5⋅10^5) — the number of users and the number of groups of friends, respectively.

Then m lines follow, each describing a group of friends. The i-th line begins with integer ki (0≤ki≤n) — the number of users in the i-th group. Then ki distinct integers follow, denoting the users belonging to the i-th group.

It is guaranteed that ∑i=1mki≤5⋅10^5

.
Output

Print n
integers. The i-th integer should be equal to the number of users that will know the news if user i

starts distributing it.
Example
Input

7 5
3 2 5 4
0
2 1 2
1 1
2 6 7

Output

4 4 1 4 4 2 2

中文:

有n个人,每个人属于一些社交圈,一个社交圈的里的人会传播消息。现在给处社交圈,问你每个人作为消息传播源的情况下,对应知道消息的人数。

代码:

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
 
typedef pair<int,int> pii;
const int maxn = 500001;
int father[maxn];
int Rank[maxn];
int n,m;
void init()
{
    for(int i=1;i<=n;i++)
    {
        father[i]=i;
        Rank[i]=1;
    }
}
 
 
int Find(int x)
{
    if(x!=father[x])
        return father[x] = Find(father[x]);
    else
        return x;
}
 
void unite(int x,int y)
{
    x = Find(x);
    y = Find(y);
    if(x==y)
        return;
    if(Rank[x]<Rank[y])
    {
        swap(x,y);
    }
    father[y]=x;
    Rank[x]+=Rank[y];
}
 
 
int main()
{
    ios::sync_with_stdio(false);
    while(cin>>n>>m)
    {
        init();
        int c;
        for(int i=1;i<=m;i++)
        {
            cin>>c;
            int mark;
            if(c)
            {
                int val;
                cin>>mark;
                for(int j=1;j<c;j++)
                {
                    cin>>val;
                    unite(mark,val);
                }
            }
        }
        for(int i=1;i<=n;i++)
        {
            int x = Find(i);
            if(i!=n)
            cout<<Rank[x]<<" ";
            else
                cout<<Rank[x]<<endl;
        }
 
    }
    return 0;
}

解答:
裸的并查集,把按秩合并的部分改成人数就完事了

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