安慰奶牛(Cheering up the Cow G) 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 <numeric>
#include <algorithm>
using namespace std;

struct Edge {
    int u, v;
    long long w;
    bool operator<(const Edge& o) const { return w < o.w; }
};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n, m;
    if (!(cin >> n >> m)) return 0;
    vector<long long> c(n + 1);
    long long minC = (1LL << 60);
    for (int i = 1; i <= n; ++i) {
        cin >> c[i];
        minC = min(minC, c[i]);
    }
    vector<Edge> edges(m);
    for (int i = 0; i < m; ++i) {
        int u, v;
        long long l;
        cin >> u >> v >> l;
        edges[i] = {u, v, 2LL * l + c[u] + c[v]};
    }
    sort(edges.begin(), edges.end());
    vector<int> p(n + 1);
    iota(p.begin(), p.end(), 0);
    auto find = [&](int x) {
        while (p[x] != x) x = p[x] = p[p[x]];
        return x;
    };
    long long ans = minC;
    for (const auto& e : edges) {
        int ru = find(e.u), rv = find(e.v);
        if (ru != rv) {
            p[ru] = rv;
            ans += e.w;
        }
    }
    cout << ans << "\n";
    return 0;
}