2020-08-21

ccf csp认证 201503-2 java 数字排序 100分

代码能力较差，希望可以得到大家的指导。一起努力，一起进步。

这道题，我用了map来储存数字。并且根据map中的value对map排序。

推荐大家看这篇博文，我找了几篇，这个不错。

https://blog.youkuaiyun.com/xHibiki/article/details/82938480?utm_medium=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.channel_param&depth_1-utm_source=distribute.pc_relevant.none-task-blog-BlogCommendFromMachineLearnPai2-2.channel_param

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Scanner;



public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int[] a = new int[n];
		for (int i = 0; i < a.length; i++) {
			a[i] = sc.nextInt();
		}
		Arrays.sort(a);
		Map<Integer,Integer> map = new HashMap<>();
		
		for (int i = 0; i < a.length; i++) {
			if(map.containsKey(a[i])){
				int count = map.get(a[i])+1;
				map.put(a[i], count);
				
			}else{
				
				map.put(a[i], 1);
			}
		}
		List<Map.Entry<Integer, Integer>> list = new ArrayList<Map.Entry<Integer, Integer>>(map.entrySet());
		Collections.sort(list,new Comparator<Map.Entry<Integer, Integer>>() {

			@Override
			public int compare(Entry<Integer, Integer> o1,
					Entry<Integer, Integer> o2) {
				// TODO Auto-generated method stub
				return o2.getValue().compareTo(o1.getValue());
			}

			
		});
		 for (int i = 0; i < list.size(); i++) {
	            System.out.println(list.get(i).getKey() + " " + list.get(i).getValue());
	        }  
	}
}