华为OD机试 - 数组去重和排序-多条件排序（JAVA 2025A卷）

import java.util.*;
import java.util.stream.Collectors;

public class DemoTest10 {

    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            int[] arr = Arrays.stream(sc.nextLine().split(",")).mapToInt(Integer::parseInt).toArray();
            // 依赖LinkedHashMap保证次数一样时按照首次插入的顺序排序
            solve(arr);
            // 多条件排序
            solve2(arr);
        }
    }

    private static void solve(int[] arr) {
        HashMap<Integer,Integer> map  = new LinkedHashMap<>();
        for(int a: arr){
            map.put(a,map.getOrDefault(a,0)+1);
        }
        List<Map.Entry<Integer, Integer>> collect = map.entrySet().stream().sorted((e1, e2) -> e2.getValue() - e1.getValue()).collect(Collectors.toList());
        StringBuilder sb = new StringBuilder();
        collect.forEach(entry->{
            sb.append(entry.getKey()).append(",");
        });
        System.out.println(sb.substring(0,sb.length()-1));
    }

    private static void solve2(int[] arr) {
        HashMap<Integer,Integer> map  = new HashMap<>();
        HashMap<Integer,Integer> id2IndexMap = new HashMap<>();
        for(int i=0;i< arr.length; i++){
            map.put(arr[i],map.getOrDefault(arr[i],0)+1);
            if(!id2IndexMap.containsKey(arr[i])){
                id2IndexMap.put(arr[i],i);
            }
        }
        List<Map.Entry<Integer, Integer>> collect = map.entrySet().stream()
                .sorted((e1, e2) -> {
                    if(Objects.equals(e1.getValue(), e2.getValue())){
                        return id2IndexMap.get(e1.getKey()) - id2IndexMap.get(e2.getKey());
                    }
                    return e2.getValue() - e1.getValue();
                }).collect(Collectors.toList());
        StringBuilder sb = new StringBuilder();
        collect.forEach(entry->{
            sb.append(entry.getKey()).append(",");
        });
        System.out.println(sb.substring(0,sb.length()-1));
    }
}