题解 | #【模板】最小生成树#

克鲁斯卡尔模板。

#include<bits/stdc++.h>
// #define int long long
#define double long double
#define x first
#define y second
using namespace std;
typedef long long LL;
typedef long long ll;
typedef pair<int, int> PII;
const int N = 5e5 + 10;
const int M = 1e3 + 10;
int mod = 1e9 + 7;
struct Link {
    int u, v, w, id;
} s[N];
int root[N];
int find(int x) {
    if (root[x] == x) return x;
    return root[x] = find(root[x]);
}
bool cmp(Link xx, Link yy) {
    return xx.w < yy.w;
}

void solve() {
    int n, m;
    cin >> n >> m;
    for (int i = 1; i <= m; i++) {
        int u, v, w;
        cin >> u >> v >> w;
        s[i] = {u, v, w, i};
    }
    for (int i = 1; i <= n; i++) root[i] = i;
    sort(s + 1, s + m + 1, cmp);
    vector<int>ans;
    ll sum = 0, cnt = 0;
    for (int i = 1; i <= m; i++) {
        int u = find(s[i].u), v = find(s[i].v);
        if (u != v) {
            root[u] = v;
            sum += s[i].w;
            ans.push_back(s[i].id);
            cnt++;
        }
        if (cnt == n - 1) break;
    }
    cout << sum << "\n";
    for (int i = 0; i < ans.size(); i++) cout << ans[i] << " ";
}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    int _;
    _ = 1;
    //cin>>_;
    while (_--) {
        solve();
    }
}