华为OD机试-热点网站统计

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

public class Main {
    public static void main(String[] args) {
        String[] urls = {"news.qq.com", "news.sina.com.cn", "news.qq.com", "news.qq.com", "game.163.com", "game.163.com", "www.huawei.com", "www.cctv.com", "3", "www.huawei.com", "www.cctv.com", "www.huawei.com", "www.cctv.com", "www.huawei.com", "www.cctv.com", "www.huawei.com", "www.cctv.com", "www.huawei.com", "3"};
        HashMap<String, Integer> statistic = new HashMap<>();
        for (String url : urls) {
            if (url.contains(".")) {
                if (statistic.containsKey(url)) {
                    statistic.put(url, statistic.get(url) + 1);
                } else {
                    statistic.put(url, 1);
                }
            } else {
                TreeMap<Integer, List<String>> collect = statistic.entrySet().stream().collect(Collectors.groupingBy(Map.Entry::getValue, () -> new TreeMap<>((o1, o2) -> o2 - o1), Collectors.collectingAndThen(Collectors.toList(), entries -> entries.stream().map(Map.Entry::getKey).sorted().collect(Collectors.toList()))));
                ArrayDeque<String> result = new ArrayDeque<>();
                for (List<String> value : collect.values()) {
                    for (String s : value) {
                        result.offerLast(s);
                        if (result.size() == Integer.parseInt(url)) {
                            break;
                        }
                    }
                    if (result.size() == Integer.parseInt(url)) {
                        break;
                    }
                }
                System.out.println(result.stream().collect(Collectors.joining(",")));
            }
        }
    }
}