每日AC

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

struct Edge {

int x, y, z;

};

bool compare(Edge a, Edge b) {

return a.z < b.z;

}

int parent[101];

int find(int x) {

if (parent[x] != x) {
    parent[x] = find(parent[x]);
}
return parent[x];

}

void unite(int x, int y) {

int fx = find(x);
int fy = find(y);
if (fx != fy) {
    parent[fy] = fx;
}

}

int main() {

int n, m;
cin >> n >> m;
vector<Edge> edges;
for (int i = 0; i < m; i++) {
    int x, y, z;
    cin >> x >> y >> z;
    edges.push_back({x, y, z});
}
sort(edges.begin(), edges.end(), compare);

for (int i = 1; i <= n; i++) {
    parent[i] = i;
}

int sum = 0;
int count = 0;
for (Edge e : edges) {
    int fx = find(e.x);
    int fy = find(e.y);
    if (fx != fy) {
        sum += e.z;
        unite(e.x, e.y);
        count++;
        if (count == n - 1) {
            break;
        }
    }
}
cout << sum << endl;
return 0;

}

不想理了，自己复制吧