CCF-最优灌溉Java

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
//求最小生成树 用并查集
import java.util.Scanner;

public class NewOptimal {
	static Scanner sc;
	static List<Rute> list;
	static int n,m;  //n表示麦田的片数  m表示可以建立的水渠的数量
	static int[] pre;
	static String temp;
	static String[] cmd;
	static int totalcost;
	public static void main(String[] args) {
		sc = new Scanner(System.in);
		n = sc.nextInt();
		m = sc.nextInt();
		list = new ArrayList<>();
		sc.nextLine();
		pre = new int[n+1];
		for(int i=1;i<=m;i++) {
			temp = sc.nextLine();
			cmd = temp.split(" ");
			list.add(new Rute(Integer.parseInt(cmd[0]),Integer.parseInt(cmd[1]),Integer.parseInt(cmd[2])));
			pre[Integer.parseInt(cmd[0])] = Integer.parseInt(cmd[0]);
			pre[Integer.parseInt(cmd[1])] = Integer.parseInt(cmd[1]);
		}
		
		Collections.sort(list, new Comparator<Rute>() {

			@Override
			public int compare(Rute o1, Rute o2) {
				// TODO Auto-generated method stub
				//按照费用从小到大排序
				return o1.cost-o2.cost;
			}
		});
		
		for(int i=0;i<list.size();i++) {
			if(find(list.get(i).start) == find(list.get(i).end)) {
				continue;
			}
			union(list.get(i).start,list.get(i).end);
			totalcost += list.get(i).cost;
		}
		System.out.print(totalcost);
	}
	
	public static int find(int x) {
		if(pre[x] == x)
			return x;
		else
			return pre[x] = find(pre[x]);
	}
	
	public static void union(int x,int y) {
		int start = find(x);
		int end = find(y);
		if(start>end) pre[start] = end;                  
		else pre[end] = pre[start];
	}

}

class Rute{
	public int start;
	public int end;
	public int cost;
	public Rute(int start, int end, int cost) {
		this.start = start;
		this.end = end;
		this.cost = cost;
	}
}