分层图建图典题

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long
const int N = 6e5+10;
const int inf = 0x3f3f3f3f;
const int mod = 1e9+7;
int e[N],ne[N],w[N],h[N],idx;
void add(int a,int b,int c){
	e[idx] = b,ne[idx] = h[a],w[idx] = c,h[a] = idx++;
}
int n,m;
int dist[N];
bool vis[N];
struct Node{
	int id,d;
	bool operator<(const Node&W)const{
		return d>W.d;
	}
};


void dijkstra()
{
	
	memset(dist,0x3f,sizeof dist);
	dist[1] = 0;
	priority_queue<Node>heap;
	heap.push({1,0});
	
	while(heap.size()){
		
		auto t = heap.top();
		heap.pop();
		int ver = t.id,distance = t.d;
		
		if(vis[ver])continue;
		vis[ver] = true;
		for(int i=h[ver];~i;i=ne[i]){
			int j = e[i];
			if(dist[j]>distance+w[i]){
				dist[j] = distance + w[i];
				heap.push({j,dist[j]});
			}
		}
	}
	
	cout<<dist[n] - min({dist[n],dist[n+n],dist[n+n+n]});
	
	
	
	
}

void solve()
{
	cin>>n>>m;
	memset(h,-1,sizeof h);
	for(int i=1;i<=m;i++){
		int a,b,c,d;cin>>a>>b>>c>>d;
		if(d==1){
			add(a,b+n,c),add(b,a+n,c);
			add(a+n,b+n+n,c),add(b+n,a+n+n,c);
			
		}else{
			add(a,b,c),add(b,a,c);
			add(a+n,b+n,c),add(b+n,a+n,c);
			add(a+n+n,b+n+n,c),add(b+n+n,a+n+n,c);
		}
	}
	
	dijkstra();

	
	
	

}

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