Kruskal 模板

#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;
const int MAXN = 110000;
struct Edge
{
    int f, t, d;
}es[MAXN];
int n, m, fa[MAXN];

int find(int x)
{
    return fa[x] == x ? x : fa[x] = find(fa[x]);
}

bool cmp(Edge a, Edge b)
{
    return a.d < b.d;
}

int main()
{
    scanf("%d%d", &n, &m);
    for(int i = 1; i <= n; i++)
        fa[i] = i;
    for(int i = 1; i <= m; i++)
    {
        int a, b, c;
        scanf("%d%d%d", &a, &b, &c);
        es[i].f = a;
        es[i].t = b;
        es[i].d = c; 
    }
    sort(es + 1, es + 1 + m, cmp);
    long long ans = 0;
    for(int i = 1; i <= m; i++)
    {
        int x = find(es[i].f);
        int y = find(es[i].t);
        if(x != y)
        {
            ans += es[i].d;
            fa[x] = y;
        }
    }
    printf("%lld", ans);
    return 0;
}