蓝桥杯每日一题-图书排序

这个题我一开始想着用Map类型，但是发现map类型没办法排序，于是各种尝试之后使用Book类+Comparable接口实现了这个功能。

题目链接如下：
图书排序
AC代码如下：

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Scanner;
import java.util.*;
// 1:无需package
// 2: 类名必须Main, 不可修改
class Book implements Comparable{
	private Integer id;
	private Integer quan;
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public Integer getQuan() {
		return quan;
	}
	public void setQuan(Integer quan) {
		this.quan = quan;
	}
	public Book(Integer id, Integer quan) {
		super();
		this.id = id;
		this.quan = quan;
	}
	@Override
	public int compareTo(Object o) {
		// TODO Auto-generated method stub
		Book book = (Book)o;
		if (this.quan-book.quan>0) {
			return 1;
		}
		if (this.quan-book.quan==0) {
			return this.id.compareTo(book.id);
		}
		
		return -1;
	}
	
}
public class Main {
    public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		int n = scanner.nextInt();
		TreeSet tSet = new TreeSet<>();
		for(int i=0;i<n;i++) {
			int id = scanner.nextInt();
			int quan = scanner.nextInt();
			tSet.add(new Book(id, quan));
		}
		Iterator iterator = tSet.iterator();
		while(iterator.hasNext()) {
			Book book = (Book) iterator.next();
			System.out.println(book.getId());
		}
	}
}