G. Welcome to Join the Online Meeting!【CCPC2024哈尔滨站】

G. Welcome to Join the Online Meeting

思路:

挺简单的BFS思路
图论题写的比较少，算是补题吧

代码:

#include <bits/stdc++.h>
#define endl '\n'
#define int long long 
#define pb push_back
#define pii pair<int,int>
const int MOD = 1e9+7;
const int INF = 0x3f3f3f3f;
typedef long long ll;
using namespace std;
const int N = 200010;
int n,m,k;
int vis[N];
int busy[N];
int bzs=0;
vector<int> lj[N];

int bfs1(int cjz){
	int cnt=1;
	queue<int> qu;
	qu.push(cjz);
	vis[cjz]=1;
	while(!qu.empty()){
		bool flag = 0;
		int f = qu.front();
		qu.pop();
		for(int e:lj[f]){
			if(vis[e])continue;
			cnt++;
			vis[e]=1;
			if(!busy[e]) qu.push(e);
			flag=1;
		}
		if(flag)bzs++;
	}
	return cnt;
}
void bfs2(int cjz){
	queue<int> qu;
	qu.push(cjz);
	vis[cjz]=1;
	while(!qu.empty()){
		int f = qu.front();
		qu.pop();
		vector<int> ans;
		for(int e:lj[f]){
			if(vis[e])continue;
			vis[e]=1;
			ans.push_back(e);
			if(!busy[e]) qu.push(e);
		}
		if(ans.size()>0){
			cout<<f<<" "<<ans.size()<<" ";
			for(int k:ans) cout<<k<<" ";
			cout<<endl;
		}
	}
	
}

void solve() {
	cin>>n>>m>>k;
	for(int i=1;i<=k;i++){
		int x;
		cin>>x;
		busy[x]=1;
	}
	for(int i=1;i<=m;i++){
		int x,y;
		cin>>x>>y;
		lj[x].pb(y);
		lj[y].pb(x);
	}
	int cjz=0;
	for(int i=1;i<=n;i++){
		if(busy[i]==0){
			cjz=i;
			break;
		}
	}
	if(cjz==0){
		cout<<"No";return;
	}
	int cnt=bfs1(cjz);
	if(cnt==n){
		cout<<"Yes"<<endl<<bzs<<endl;
	}else{
		cout<<"No";return;
	}
	memset(vis,0,sizeof(vis));
	bfs2(cjz);
}

signed main() {
	cin.tie(0)->ios::sync_with_stdio(0);
	int T = 1;
	while (T--) {
		solve();
	}
	return 0;
}