题解 | #小红送外卖#

import java.io.*;
import java.util.*;

public class Main {
    static class Edge {
        int v, w;
        Edge(int v, int w) {
            this.v = v;
            this.w = w;
        }
    }

    static void solve() {
        int n = in.nextInt(), m = in.nextInt(), q = in.nextInt();  

        List<List<Edge>> graph = new ArrayList<>();
        for (int i = 0; i <= n; i++) {
            graph.add(new ArrayList<>());
        }

        for (int i = 0; i < m; i++) {
            int u = in.nextInt(), v = in.nextInt(), w = in.nextInt();
            graph.get(u).add(new Edge(v, w));
            graph.get(v).add(new Edge(u, w));  
        }

        long[] dis = new long[n + 1];
        Arrays.fill(dis, Long.MAX_VALUE);  
        dis[1] = 0;  

        PriorityQueue<long[]> pq = new PriorityQueue<>(Comparator.comparingLong(a -> a[0]));
        pq.add(new long[] {0, 1}); 

        while (!pq.isEmpty()) {
            long[] cur = pq.poll();
            long d = cur[0];  
            int u = (int) cur[1];  
            
            if (d > dis[u]) continue;

            for (Edge edge : graph.get(u)) {
                int v = edge.v;
                int weight = edge.w;

                if (dis[u] + weight < dis[v]) {
                    dis[v] = dis[u] + weight;
                    pq.add(new long[] {dis[v], v});
                }
            }
        }

        long total = 0;
        for (int i = 0; i < q; i++) {
            int school = in.nextInt();
            if (dis[school] != Long.MAX_VALUE) {
                total += dis[school] * 2; 
            }
        }
        out.println(total);  
    }

    public static void main(String[] args) {
        solve();
        out.flush();
    }

    static FastReader in = new FastReader();
    static PrintWriter out = new PrintWriter(System.out);

    static class FastReader {
        static BufferedReader br;
        static StringTokenizer st;

        FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            String str = "";
            while (st == null || !st.hasMoreElements()) {
                try {
                    str = br.readLine();
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
                st = new StringTokenizer(str);
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }
    }
}