求条玄关50pts

#include<bits/stdc++.h>
using namespace std;
int n,r;
const int N=5005;
vector<pair<int,int> > G[N];
inline void dij(){
	priority_queue<pair<int,int>,vector<pair<int,int> >,greater<pair<int,int> > > q;
	q.push({0,1});
	int dist[N];
	int cdist[N];
	memset(dist,0x3f3f3f,sizeof(dist));
	memset(cdist,0x3f3f3f,sizeof(cdist));
	dist[1]=cdist[1]=0;
	bool vis[N];
	vis[1]=1;
	while(!q.empty()){
		auto u=q.top().second;
		vis[u]=0;
		q.pop();
		for(auto v:G[u]){
			if(dist[u]+v.second<dist[v.first]){
				cdist[v.first]=dist[v.first];
				dist[v.first]=dist[u]+v.second;
				if(!vis[v.first]){
					vis[v.first]=1;
					q.push({dist[v.first],v.first});
				}
			}
			else if(dist[u]+v.second<cdist[v.first]&&dist[u]+v.second>dist[v.first]){
				cdist[v.first]=dist[u]+v.second;
			}
		}
	}
	cout<<cdist[n];
}
int main(){
	cin>>n>>r;
	for(int i=1;i<=r;i++){
		int u,v,w;
		cin>>u>>v>>w;
		G[u].push_back({v,w});
		G[v].push_back({u,w});
	}
	dij();
	return 0;
}