'commit'

TangDou/AcWing_TiGao/T3/MiniPath/1126.cpp

@@ -0,0 +1,58 @@
+#include <bits/stdc++.h>
+using namespace std;
+
+const int N = 2010;
+const int M = 2e5 + 10;
+
+typedef pair<double, int> PDI; // 堆中数值是浮点数，注意区别
+
+int n, m;
+double dis[N];
+bool st[N];
+
+int h[N], e[M], ne[M], idx;
+double w[M]; // 边权为浮点数,与一般的题目有区别
+void add(int a, int b, double c) {
+    e[idx] = b, w[idx] = c, ne[idx] = h[a], h[a] = idx++;
+}
+int S, T;
+void dijkstra() {
+    priority_queue<PDI> q; // 大顶堆
+    dis[S] = 1;
+    q.push({1, S});
+
+    while (q.size()) {
+        auto t = q.top();
+        q.pop();
+        int u = t.second;
+        if (st[u]) continue;
+        st[u] = true;
+
+        for (int i = h[u]; ~i; i = ne[i]) {
+            int v = e[i];
+            double a = 1 - w[i];
+            if (dis[v] < dis[u] * a) {
+                dis[v] = dis[u] * a;
+                q.push({dis[v], v});
+            }
+        }
+    }
+}
+
+int main() {
+    memset(h, -1, sizeof h);
+    cin >> n >> m;
+
+    while (m--) {
+        int a, b, c;
+        cin >> a >> b >> c;
+        double w = c * 0.01;
+        add(a, b, w), add(b, a, w);
+    }
+
+    cin >> S >> T;
+
+    dijkstra();
+    printf("%.8lf\n", 100 / dis[T]);
+    return 0;
+}