Java实现思路：创建一个志愿者内部类，包括编号、服务时长、难度、贡献度属性。使用ArrayList将多个志愿者对象联系在一起。使用Collection的sort方法，重写compare方法进行按规则比较。

Java代码：

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Scanner;
public class Main{static class volunteer{public int id;public int t;public int k;public int conty;public volunteer(int id,int t, int k) {this.id = id;this.t = t;this.k = k;conty = t*k;}}public static void main(String[] args) {Scanner sc = new Scanner(System.in);int n = sc.nextInt();List<volunteer> list = new ArrayList<>();for (int i = 1; i <= n; i++) {list.add(new volunteer(i,sc.nextInt(),sc.nextInt()));}Collections.sort(list, new Comparator<volunteer>() {public int compare(volunteer o1, volunteer o2) {if (o1.conty != o2.conty) {return o2.conty - o1.conty;}else if(o1.t != o2.t) {return o2.t - o1.t;}else {return o1.id - o2.id;}}});for (int i = 0; i < list.size(); i++) {System.out.print(list.get(i).id+" ");}}
}