最佳地点(Best Spot S) 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 <algorithm>
using namespace std;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int p, f, c;
    if (!(cin >> p >> f >> c)) return 0;
    vector<int> fav(f);
    for (int i = 0; i < f; ++i) cin >> fav[i];
    const long long INF = (1LL << 58);
    vector<vector<long long>> d(p + 1, vector<long long>(p + 1, INF));
    for (int i = 1; i <= p; ++i) d[i][i] = 0;
    for (int i = 0; i < c; ++i) {
        int u, v;
        long long w;
        cin >> u >> v >> w;
        d[u][v] = min(d[u][v], w);
        d[v][u] = min(d[v][u], w);
    }
    for (int k = 1; k <= p; ++k) {
        for (int i = 1; i <= p; ++i) {
            if (d[i][k] >= INF) continue;
            for (int j = 1; j <= p; ++j) {
                if (d[i][k] + d[k][j] < d[i][j]) {
                    d[i][j] = d[i][k] + d[k][j];
                }
            }
        }
    }
    long long best_sum = INF;
    int best_u = 1;
    for (int u = 1; u <= p; ++u) {
        long long s = 0;
        for (int x : fav) s += d[u][x];
        if (s < best_sum) {
            best_sum = s;
            best_u = u;
        }
    }
    cout << best_u << "\n";
    return 0;
}