AcWing 1137. Select the best line solution (the shortest circuit)

AcWing 1137. Select the best route
Their thinking ： Each starting point will run once, and the shortest circuit will timeout , Then establish a virtual starting point , The distance between this initial point and all starting points is 0, So the shortest path from the virtual starting point to the end point is the shortest and shortest path among all the starting points

#include<bits/stdc++.h>

using namespace std;

const int N = 1010, M = 40010, INF = 0x3f3f3f3f;

int n, m, T;
int h[N], e[M], ne[M], w[M], idx;
int d[N];
int q[N];
bool st[N];

void add(int a, int b, int c){
    
	e[idx] = b;
	w[idx] = c;
	ne[idx] = h[a];
	h[a] = idx ++ ;
}

int spfa(){
    
	
	memset(d, 0x3f, sizeof d);
	int hh = 0, tt = 1;
	q[0] = 0;
	d[0] = 0;
	st[0] = true;
	
	while(tt != hh){
    
		int t = q[hh ++ ];
		if(hh == N) hh = 0;
		st[t] = false;
		
		for(int i = h[t]; ~i; i = ne[i]){
    
			int j = e[i];
			if(d[j] > d[t] + w[i]){
    
				d[j] = d[t] + w[i];
				if(!st[j]){
    
					q[tt ++ ] = j;
					if(tt == N) tt = 0;
					st[j] = true;
				}
			}
		}
	}
	
	if(d[T] > 1e9) return -1;
	else return d[T];
} 

int main()
{
    
	while(scanf("%d%d%d", &n, &m, &T) != -1){
    
		memset(h, -1, sizeof h); 
		idx = 0;
		while(m -- ){
    
			int a, b, c;
			scanf("%d%d%d", &a, &b, &c);
			add(a, b, c);
		}
		int w;
		cin>>w;
		while(w -- ){
    
			int ver;
			scanf("%d", &ver);
			add(0, ver, 0);
		}
		cout<<spfa()<<endl;
	}
	return 0;
}