byd锅

\(Dijkstra\) 算法，记录最短路的路径。
保证 \(Dijkstra\) 没问题，锅在记录路径。
//NEW中夹的内容是记录路径的代码。

#include <bits/stdc++.h>
 
using namespace std;
 
struct Edge
{
    int v, w;
    // v --> to, w --> value
    friend bool operator<(const Edge &x, const Edge &y)
    {
        return x.w > y.w; 
    }
};
 
const int maxn = 1e5 + 5;
 
vector<Edge> e[maxn];
 
//NEW
stack<int> out;
int pre[maxn];
//NEW
 
priority_queue<Edge> q;
int dis[maxn], vis[maxn], n, m, s;
 
void dijkstra()
{
    dis[s] = 0;
    q.push({s, 0});
    while (!q.empty())
    {
        Edge inp = q.top();
        q.pop();
        int p = inp.v;
        int tot = e[p].size();
        if (vis[p])
            continue;
 
        vis[p] = 1;
        for (int j = 0; j < tot; j++)
        {
            int v = e[p][j].v;
            if (dis[v] > dis[p] + e[p][j].w)
            {
                dis[v] = dis[p] + e[p][j].w;
                if (!vis[v])
                {
                    q.push(Edge{v, dis[v]});
 
                    //NEW
                    pre[v] = p;
                    //NEW
 
                }
            }
        }
    }
    return;
}
 
int main()
{
    cin >> n >> m;
    s = 1;
    for (int i = 1; i <= n; i++)
    {
        dis[i] = 2147483647;
 
        //NEW
        pre[i] = -1;
        //NEW
 
    }
 
    for (int i = 1; i <= m; i++)
    {
        int x, y, w;
        cin >> x >> y >> w;
        Edge inp;
        inp.v = y, inp.w = w;
        e[x].push_back({y, w});
        e[y].push_back({x, w});
    }
 
    dijkstra();
 
 
    //NEW
    for (int i = n; i != -1; i = pre[i])
    {
        out.push(i);
    }
 
    int flag = 0;
    while (!out.empty())
    {
        cout << out.top() << ' ';
        out.pop();
        flag = 1;
    }
    if(flag == 0)
        cout << -1 << ' ';
    //NEW
 
    return 0;
}