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/07_03_p1462.cpp

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+// P1462 通往奥格瑞玛的道路。城市费二分，非负道路耗血用 Dijkstra。
+#include <bits/stdc++.h>
+using namespace std;
+using ll = long long;
+int main() {
+    ios::sync_with_stdio(false); cin.tie(nullptr);
+    int n, m; ll b; if (!(cin >> n >> m >> b)) return 0;
+    vector<int> fee(n + 1), values;
+    for (int i = 1; i <= n; ++i) { cin >> fee[i]; values.push_back(fee[i]); }
+    vector<vector<pair<int,ll>>> g(n + 1);
+    for (int i = 0, u, v; i < m; ++i) {
+        ll w; cin >> u >> v >> w;
+        g[u].push_back({v,w}); g[v].push_back({u,w});
+    }
+    auto check = [&](int X) {
+        if (fee[1] > X || fee[n] > X) return false;
+        const ll INF = 1LL << 60;
+        vector<ll> dist(n + 1, INF);
+        priority_queue<pair<ll,int>, vector<pair<ll,int>>, greater<pair<ll,int>>> pq;
+        dist[1] = 0; pq.push({0,1});
+        while (!pq.empty()) {
+            auto [du,u] = pq.top(); pq.pop();
+            if (du != dist[u]) continue;
+            for (auto [v,w] : g[u]) {
+                if (fee[v] > X) continue;
+                if (du + w < dist[v]) {
+                    dist[v] = du + w; pq.push({dist[v],v});
+                }
+            }
+        }
+        return dist[n] <= b;
+    };
+    sort(values.begin(), values.end());
+    values.erase(unique(values.begin(), values.end()), values.end());
+    if (!check(values.back())) { cout << "AFK\n"; return 0; }
+    int l = 0, r = (int)values.size() - 1;
+    while (l < r) {
+        int mid = l + (r-l)/2;
+        if (check(values[mid])) r = mid; else l = mid + 1;
+    }
+    cout << values[l] << '\n';
+}