MST

#include <cstdio>
#include <algorithm>

const int M = 2222222;
const int N = 111111;

struct Edge {
    int u, v, weight;
    bool operator< (const Edge & q) const {
        return weight < q.weight;
    }
} t[M];

int p[N], n, m, ans;

int find_set(int x) {
    if (x == p[x]) {
        return x;
    } else {
        return p[x] = find_set(p[x]);
    }
}

void unite(const Edge & e) {
    int u = find_set(e.u);
    int v = find_set(e.v);
    if (u != v) {
        p[u] = v;
        ans += e.weight;
    }
}

int main() {
    scanf("%d%d", &n, &m);
    for (int i = 1; i <= n; ++i) {
        p[i] = i;
    }
    for (int i = 0; i < m; ++i) {
        scanf("%d%d%d", &t[i].u, &t[i].v, &t[i].weight);
    }
    std::sort(t, t + m);
    for (int i = 0; i < m; ++i) {
        unite(t[i]);
    }
    return 0;
}