最短网络(Agri-Net) 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;

const int INF = 1000000000;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n;
    if (!(cin >> n)) return 0;
    vector<vector<int>> g(n, vector<int>(n));
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) cin >> g[i][j];
    }
    vector<int> dist(n, INF);
    vector<char> vis(n, 0);
    dist[0] = 0;
    long long ans = 0;
    for (int step = 0; step < n; ++step) {
        int u = -1;
        for (int i = 0; i < n; ++i) {
            if (!vis[i] && (u == -1 || dist[i] < dist[u])) u = i;
        }
        vis[u] = 1;
        ans += dist[u];
        for (int v = 0; v < n; ++v) {
            if (!vis[v] && g[u][v] < dist[v]) dist[v] = g[u][v];
        }
    }
    cout << ans << "\n";
    return 0;
}