Initial commit: C++ courseware

2.Course/2.深入浅出程序设计竞赛（提高篇）/最短路/C++源码/03c_multi_source.cpp

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+// 教学扩展：非负有向图，多源最短路。
+// 输入 n m r；下一行 r 个源点编号；随后 m 行 u v w。
+// 顶点编号 1..n，允许重复源点；输出到各点的最近距离，不可达输出 -1。
+#include <iostream>
+#include <vector>
+#include <queue>
+#include <utility>
+#include <functional>
+using namespace std;
+using ll = long long;
+using State = pair<ll, int>;
+struct Edge { int to; ll w; };
+int main() {
+    ios::sync_with_stdio(false); cin.tie(nullptr);
+    int n, m, r;
+    if (!(cin >> n >> m >> r)) return 0;
+    vector<int> sources(r);
+    for (int &x : sources) cin >> x;
+    vector<vector<Edge>> g(n + 1);
+    for (int i = 0; i < m; ++i) {
+        int u, v; ll w; cin >> u >> v >> w;
+        g[u].push_back({v, w});
+    }
+    const ll INF = (1LL << 60);
+    vector<ll> dis(n + 1, INF);
+    priority_queue<State, vector<State>, greater<State>> q;
+    for (int x : sources) {
+        if (dis[x] == 0) continue;
+        dis[x] = 0;
+        q.push({0, x});
+    }
+    while (!q.empty()) {
+        State cur = q.top(); q.pop();
+        ll d = cur.first; int u = cur.second;
+        if (d != dis[u]) continue;
+        for (const auto &e : g[u]) {
+            ll nd = d + e.w;
+            if (nd < dis[e.to]) {
+                dis[e.to] = nd;
+                q.push({nd, e.to});
+            }
+        }
+    }
+    for (int i = 1; i <= n; ++i)
+        cout << (dis[i] == INF ? -1 : dis[i]) << (i == n ? '\n' : ' ');
+}