题解 | 无人机物流网络最优路径规划

#include <bits/stdc++.h>

using namespace std;

typedef pair<int,int> pii;

const int N = 1e3 + 10;
const int M = 1e6 + 10;
const int inf = 0x3f3f3f3f;

int n, m, idx, h[N], e[M], ne[M], w[M], dist[N], st, ed;
bool book[N];
vector<int> lst;

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

void dij() {
    memset(dist, 0x3f, sizeof dist);
    priority_queue<pii, vector<pii>, greater<pii>> q;
    q.push({0, st});
    dist[st] = 0;
    while( q.size() ) {
        auto [d, now] = q.top();
        q.pop();
        if(book[now]) continue;
        book[now] = true;
        for(int i=h[now]; ~i; i=ne[i]) {
            int j = e[i], k = w[i];
            if(d + k < dist[j]) {
                dist[j] = d + k;
                q.push({dist[j], j});
                if(j == ed) {
                    lst.clear();
                    lst.emplace_back(now);
                }
            } else if(d + k == dist[j] && j == ed) {
                lst.emplace_back(now);
            }
        }
    }
}

int main() {
    ios :: sync_with_stdio(false);
    cin.tie(0), cout.tie(0);

    cin >> n >> m;
    memset(h, -1, sizeof h);
    while( m -- ) {
        int a, b, c;
        cin >> a >> b >> c;
        add(a, b, c);
        add(b, a, c);
    }
    cin >> ed >> st;
    if(st == ed) {
        cout << 0 << '\n' << -1;
        return 0;
    }
    dij();
    if(dist[ed] != inf) {
        cout << dist[ed] << '\n';
        for(auto &num : lst) cout << num << ' ';
    } else {
        cout << -1 << '\n' << -1;
    }
    return 0;
}
// 64 位输出请用 printf("%lld")

从终点向起点做一遍dijkstra算法，同时维护一下可以更新起点最短距离的上一个点集即可