题解（包AC）

#include <bits/stdc++.h>
using namespace std;

const int MAXN = 110;
const int INF = 0x3f3f3f3f;

vector<pair<int, int>> adj[MAXN]; // 邻接表：adj[u] 存储 {v, weight}
int dist[MAXN];                   // 距离数组

void dijkstra(int start, int n) {
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;

    fill(dist, dist + n + 1, INF);
    dist[start] = 0;
    pq.push({0, start});

    while (!pq.empty()) {
        int d = pq.top().first;
        int u = pq.top().second;
        pq.pop();

        if (d > dist[u]) continue; // 已经找到更短路径，跳过

        for (auto &edge : adj[u]) {
            int v = edge.first;
            int w = edge.second;
            if (dist[v] > dist[u] + w) {
                dist[v] = dist[u] + w;
                pq.push({dist[v], v});
            }
        }
    }
}

int main() {
    int n, m;
    cin >> n >> m;

    for (int i = 0; i < m; i++) {
        int a, b, c;
        cin >> a >> b >> c;
        adj[a].push_back({b, c});
        adj[b].push_back({a, c}); // 无向图
    }

    dijkstra(1, n);

    cout << dist[n] << endl;

    return 0;
}