最小花费(Minimum Cost) 题解

思路分析

按题目要求使用对应数据结构与算法模拟/递推求解，注意数据范围边界与时间复杂度。

参考代码

#include <iostream>
#include <vector>
#include <queue>
#include <iomanip>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    if (!(cin >> n >> m)) return 0;
    vector<vector<pair<int, double>>> adj(n + 1);
    for (int i = 0; i < m; ++i) {
        int u, v, z;
        cin >> u >> v >> z;
        double rate = 1.0 - z / 100.0;
        adj[u].push_back({v, rate});
        adj[v].push_back({u, rate});
    }
    int s, t;
    cin >> s >> t;
    vector<double> best(n + 1, 0.0);
    priority_queue<pair<double, int>> pq;
    best[s] = 1.0;
    pq.push({1.0, s});
    while (!pq.empty()) {
        auto [d, u] = pq.top();
        pq.pop();
        if (d < best[u] - 1e-14) continue;
        if (u == t) break;
        for (auto& edge : adj[u]) {
            int v = edge.first;
            double nd = d * edge.second;
            if (nd > best[v] + 1e-14) {
                best[v] = nd;
                pq.push({nd, v});
            }
        }
    }
    cout << fixed << setprecision(8) << (100.0 / best[t]) << "\n";
    return 0;
}