[백준] 6497번 전력난 (gold 4

import java.io.*;
import java.util.*;

class Point{
    int y;
    int l;
    public Point(int y, int l){
        this.y=y;
        this.l=l;
    }
}
public class Main{
    public static void main(String[] args) throws IOException{
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(System.out));
        PriorityQueue<Point> que=new PriorityQueue<>(new Comparator<Point>(){
            public int compare(Point o1, Point o2){
                return o1.l-o2.l;
            }
        });
        while(true) {
            que.clear(); //까먹음. 비우지 않으면 전의 값들로 인해 index오류 발생
            StringTokenizer st = new StringTokenizer(br.readLine());
            int n = Integer.valueOf(st.nextToken());
            int m = Integer.valueOf(st.nextToken());
            if(n+m==0){
                break;
            }
            ArrayList<Point>[] map = new ArrayList[n];
            for (int i = 0; i < n; i++) {
                map[i] = new ArrayList<>();
            }
            int answer=0;
            for (int i=0; i<m; i++){
                st=new StringTokenizer(br.readLine());
                int x=Integer.valueOf(st.nextToken());
                int y=Integer.valueOf(st.nextToken());
                int l=Integer.valueOf(st.nextToken());

                map[x].add(new Point(y,l));
                map[y].add(new Point(x,l));
                answer+=l;
            }

            boolean[] visit = new boolean[n];
            int visitN=0;
            que.offer(new Point(0,0));
            while(!que.isEmpty()){
                Point a=que.poll();
                if(visit[a.y]){
                    continue;
                }
                visitN++;
                answer-=a.l;
                visit[a.y]=true;
                if(visitN==n){
                    break;
                }

                for(int i=0; i<map[a.y].size(); i++){
                    Point temp=map[a.y].get(i);
                    if(visit[temp.y]){
                        continue;
                    }
                    que.offer(new Point(temp.y, temp.l));
                }
            }
            bw.write(answer+"\n");
        }
        bw.flush();
    }
}