hdu 3371 Connect the Cities

#include<iostream>
#include<cstdio>
#include<vector>
#include<algorithm>
using namespace std;
const int MAX=1000000;
struct node
{
    int left,right,cost;
}road[MAX];

bool cmp(node x,node y){return x.cost<y.cost;}

int p[MAX],m,n;

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

int kruskal()
{
    int ans=0,k=0;
    for (int i=0;i<=n;i++) p[i]=i;
    for (int i=0;i<m;i++)
    {
        int x=find(road[i].left);
        int y=find(road[i].right);
        if(x!=y)
        {
            ans+=road[i].cost;
            p[x]=y;
            k++;
        }
        if (k==n-1) break;
    }
    if (k==n-1)return ans;
    else return -1;
}

int main()
{
    int x,y,c,k,num,a[500],T;
    scanf("%d",&T);
    while(T--)
    {
        scanf("%d%d%d",&n,&m,&k);
        for (int i=0;i<m;i++)
        scanf("%d%d%d",&road[i].left,&road[i].right,&road[i].cost);
        while(k--)
        {
            scanf("%d",&num);
            for (int i=0;i<num;i++) {
                scanf("%d",&a[i]);
                for (int j=0;j<i;j++)
                {
                    road[m].left=a[i];
                    road[m].right=a[j];
                    road[m].cost=0;
                    m++;
                }
            }
        }
        sort(road,road+m,cmp);
        int mintree=kruskal();
        printf("%d\n",mintree);
    }
    return 0;
}