HDU 3371 Connect the Cities

并查集+set容器 Kruskal

#include <stdio.h>
#include <string.h>
#include <set>
using namespace std;
const int MAXN = 501;
struct E
{
    int x,y;
    int weight;
};
E edge[25001];
int father[MAXN];

int cmp(const void *d1,const void *d2){
    return (*(E*)d1).weight - (*(E*)d2).weight;
}

void makeSet(int n){
    for(int i = 0; i <= n; i++)
        father[i] = i;
}

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

void merge(int x, int y){
    if(x > y){
        father[x] = y;
    } else {
        father[y] = x;
    }
}

int main(){
    set<int> s;
    int cas,n,m,k,cost;
    scanf("%d",&cas);
    while( cas-- ){
        scanf("%d %d %d",&n, &m, &k);
        s.clear();
        makeSet(n);
        cost = 0;
        for(int i = 1; i <= m; i++){
            scanf("%d%d%d",&edge[i].x,&edge[i].y,&edge[i].weight);
        }
        int num,first,city;
        for(int i = 1; i <= k;i++){
            scanf("%d%d",&num,&first);
            for(int j = 1; j < num; j++){
                scanf("%d",&city);
                int xx = find(first);
                int yy = find(city);
                if(xx != yy)
                    merge(xx,yy);
            }
        }
        qsort(edge+1,m,sizeof(E),cmp);
        for(int i = 1; i <= m; i++){
            int xx = find(edge[i].x);
            int yy = find(edge[i].y);
            if(xx != yy){
                merge(xx,yy);
                cost += edge[i].weight;
            }
        }
        for(int i = 1; i <= n; i++){
            find(i);
        }
        for(int i = 1; i <= n; i++){
            s.insert(father[i]);
        }
        if(s.size() > 1){
            printf("-1\n");
        } else {
            printf("%d\n",cost);
        }
    }
    return 0;
}