Network

https://vjudge.net/contest/411012#problem/B

这sb题真的就nm离谱

割点板子题,就是建图比较sb,具体看代码吧

#include <iostream>
#include <vector>
#include <cstring>
#include <cstdio>
#include <algorithm>
#include <string>
#include <set>
using namespace std;
typedef long long ll;
const int maxn = 2e5+121;
vector<int> G[maxn];
void add(int x,int y) {
	G[x].push_back(y);
}
int n;
int dfn[maxn], low[maxn];
int cnt[maxn];
int df;

string sn;
int tarjan(int x){
	dfn[x] = low[x] = ++df;
	int f = 0;
	
	for(int i=0;i<G[x].size();i++){
		int p = G[x][i];
		if(!dfn[p]){
			tarjan(p);
			low[x] = min(low[x],low[p]);
			
			if(dfn[x] <= low[p]){
				f++;
				if(x != 1 || f > 1){
					cnt[x] = 1;
				}
			}		
		}	
		else{
			low[x] = min(low[x],dfn[p]);
		}
	}
	
	
	return 0;
}
int main() {
	while(cin>>n && n) {
		for(int i=0; i<=n+11; i++) {
			G[i].clear();
			dfn[i] = low[i] = 0;
			cnt[i] = 0;
		}
		df = 0;
		
		getchar();
		while(1){
			int f = 0;
			int ans = 0;
			int be;
			getline(cin,sn);
			if(sn == "0") break;
			
			for (int i = 0; i < sn.size(); i++) {
				if(sn[i] >= '0' && sn[i] <= '9') {
					ans *= 10;
					ans += sn[i] - '0';
				} 
				else {
					if(f == 0) {
						be = ans;
						f = 1;
					} 
					else {
						add(be, ans);
						add(ans, be);
					}
					ans = 0;
				}
			}
			add(be,ans);
			add(ans,be);
		}
		
		tarjan(1);
		int ans = 0;
		for(int i=1;i<=n;i++){
			if(cnt[i])  ans++;
		}
		cout<<ans<<endl;
	}
	return 0;
}