90pts 求条

#include<bits/stdc++.h>
#define int long long
using namespace std;
struct node
{
	int value;
	int id;
};
int n,m;
vector<node> G[5003];
bool book[5003];
int dis[5003];
int cnt[5003];
bool spfa()
{
	queue<int> q;
	q.push(0);book[0]=true;
	for(int i=1;i<=n;i++)
	{
		dis[i]=INT_MAX;
	}
	while(!q.empty())
	{
		int x=q.front();q.pop();
		book[x]=false;
		for(node v:G[x])
		{
			if(dis[x]+v.value<dis[v.id])
			{
				dis[v.id]=dis[x]+v.value;
				if(book[v.id]==false)
				{
					book[v.id]=true;
					q.push(v.id);
					cnt[v.id]++;
					if(cnt[v.id]>n+1) return false;
				}
			}
		}
	}
	return true;
}
signed main()
{

	cin>>n>>m;
	for(int i=1;i<=m;i++)
	{
		int opt,a,b,c;
		cin>>opt>>a>>b;
		if(opt==1)
		{
			cin>>c;
			G[b].push_back(node{c,a});
		}
		else if(opt==2)
		{
			cin>>c;
			G[a].push_back(node{-c,b});
		}
		else
		{
			G[a].push_back(node{0,b});
			G[b].push_back(node{0,a});
		}
	}
	for(int i=1;i<=n;i++)
	{
		G[0].push_back(node{0,i});
	}
	if(spfa())
	{
		cout<<"Yes\n";
	}
	else
	{
		cout<<"No";
	}
	return 0;
}