HDU 1233 畅通工程2

//最基础的并查集 最小生成树 
#include <stdio.h>
#include <stdlib.h> 
const int MAX = 101;
struct E{
    int x,y,weight;
};
E edge[5001];
int father[MAX];
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){
    return father[x] == x ? x : father[x] = find(father[x]);
}
int main(){
    int N,cost;
    while(scanf("%d",&N) == 1){
        if(N == 0)
            break;
        makeSet(N);
        cost = 0;
        for(int i = 1; i <= N*(N-1)/2; i++){
            scanf("%d%d%d",&edge[i].x,&edge[i].y,&edge[i].weight);
        }
        qsort(edge+1,N*(N-1)/2,sizeof(E),cmp);    //一开始写成edge 一直错 因为0号单元没用 
        for(int i = 1; i <= N*(N-1)/2; i++){
            int x = find(edge[i].x);
            int y = find(edge[i].y);
            if(x != y ){
                cost += edge[i].weight;
                if(x > y)
                    father[x] = y;
                else
                    father[y] = x;
            }
        }
        printf("%d\n",cost);
    }
    return 0;
}